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Yudong Jin 2023-01-11 19:26:19 +08:00 committed by GitHub
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6
.gitignore vendored
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# Editor
.vscode/
.idea/
cmake-build-debug/
hello-algo.iml
*.dSYM/
# mkdocs files
site/
@ -13,6 +16,3 @@ docs/overrides/
# python files
__pycache__
# iml
hello-algo.iml

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.prettierrc Normal file
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{
"tabWidth": 4,
"useTabs": false
}

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codes/c/CMakeLists.txt Normal file
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cmake_minimum_required(VERSION 3.10)
project(hello_algo C)
set(CMAKE_C_STANDARD 11)
include_directories(./include)
add_subdirectory(include)
add_subdirectory(chapter_computational_complexity)
add_subdirectory(chapter_array_and_linkedlist)
add_subdirectory(chapter_sorting)
add_subdirectory(chapter_tree)

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codes/c/chapter_array_and_linkedlist/CMakeLists.txt Normal file
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add_executable(array array.c)

112
codes/c/chapter_array_and_linkedlist/array.c Normal file
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/**
* File: array.c
* Created Time: 2022-12-20
* Author: MolDuM (moldum@163.com)
*/
#include "../include/include.h"
/* 随机返回一个数组元素 */
int randomAccess(int* nums, int size) {
// 在区间 [0, size) 中随机抽取一个数字
int randomIndex = rand() % size;
// 获取并返回随机元素
int randomNum = nums[randomIndex];
return randomNum;
}
/* 扩展数组长度 */
int* extend(int* nums, int size, int enlarge) {
// 初始化一个扩展长度后的数组
int* res = (int *)malloc(sizeof(int) * (size + enlarge));
// 将原数组中的所有元素复制到新数组
for (int i = 0; i < size; i++) {
res[i] = nums[i];
}
// 初始化扩展后的空间
for (int i = size; i < size + enlarge; i++) {
res[i] = 0;
}
// 返回扩展后的新数组
return res;
}
/* 在数组的索引 index 处插入元素 num */
void insert(int* nums, int size, int num, int index) {
// 把索引 index 以及之后的所有元素向后移动一位
for (int i = size - 1; i > index; i--) {
nums[i] = nums[i - 1];
}
// 将 num 赋给 index 处元素
nums[index] = num;
}
/* 删除索引 index 处元素 */
void removeItem(int* nums, int size, int index) {
// 把索引 index 之后的所有元素向前移动一位
for (int i = index; i < size - 1; i++) {
nums[i] = nums[i + 1];
}
}
/* 遍历数组 */
void traverse(int* nums, int size) {
int count = 0;
// 通过索引遍历数组
for (int i = 0; i < size; i++) {
count++;
}
}
/* 在数组中查找指定元素 */
int find(int* nums, int size, int target) {
for (int i = 0; i < size; i++) {
if (nums[i] == target)
return i;
}
return -1;
}
/* Driver Code */
int main() {
/* 初始化数组 */
int size = 5;
int arr[5];
printf("数组 arr = ");
PrintArray(arr, size);
int nums[5] = { 1, 3, 2, 5, 4 };
printf("数组 nums = ");
PrintArray(nums, size);
/* 随机访问 */
int randomNum = randomAccess(nums, size);
printf("在 nums 中获取随机元素 %d", randomNum);
/* 长度扩展 */
int enlarge = 3;
int* res = extend(nums, size, enlarge);
size += enlarge;
printf("将数组长度扩展至 8 ，得到 nums = ");
PrintArray(res, size);
/* 插入元素 */
insert(res, size, 6, 3);
printf("在索引 3 处插入数字 6 ，得到 nums = ");
PrintArray(res, size);
/* 删除元素 */
removeItem(res, size, 2);
printf("删除索引 2 处的元素，得到 nums = ");
PrintArray(res, size);
/* 遍历数组 */
traverse(res, size);
/* 查找元素 */
int index = find(res, size, 3);
printf("在 res 中查找元素 3 ，得到索引 = %d\n", index);
return 0;
}

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codes/c/chapter_computational_complexity/CMakeLists.txt Normal file
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add_executable(time_complexity time_complexity.c )
add_executable(worst_best_time_complexity worst_best_time_complexity.c)

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codes/c/chapter_computational_complexity/time_complexity.c Normal file
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/**
* File: time_complexity.c
* Created Time: 2023-01-03
* Author: sjinzh (sjinzh@gmail.com)
*/
#include "../include/include.h"
/* 常数阶 */
int constant(int n) {
int count = 0;
int size = 100000;
int i = 0;
for (int i = 0; i < size; i++) {
count ++;
}
return count;
}
/* 线性阶 */
int linear(int n) {
int count = 0;
for (int i = 0; i < n; i++) {
count ++;
}
return count;
}
/* 线性阶（遍历数组） */
int arrayTraversal(int *nums, int n) {
int count = 0;
// 循环次数与数组长度成正比
for (int i = 0; i < n; i++) {
count ++;
}
return count;
}
/* 平方阶 */
int quadratic(int n)
{
int count = 0;
// 循环次数与数组长度成平方关系
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
count ++;
}
}
return count;
}
/* 平方阶（冒泡排序） */
int bubbleSort(int *nums, int n) {
int count = 0; // 计数器
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (int i = n - 1; i > 0; i--) {
// 内循环：冒泡操作
for (int j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
int tmp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = tmp;
count += 3; // 元素交换包含 3 个单元操作
}
}
}
return count;
}
/* 指数阶（循环实现） */
int exponential(int n) {
int count = 0;
int bas = 1;
// cell 每轮一分为二，形成数列 1, 2, 4, 8, ..., 2^(n-1)
for (int i = 0; i < n; i++) {
for (int j = 0; j < bas; j++) {
count++;
}
bas *= 2;
}
// count = 1 + 2 + 4 + 8 + .. + 2^(n-1) = 2^n - 1
return count;
}
/* 指数阶（递归实现） */
int expRecur(int n) {
if (n == 1) return 1;
return expRecur(n - 1) + expRecur(n - 1) + 1;
}
/* 对数阶（循环实现） */
int logarithmic(float n) {
int count = 0;
while (n > 1) {
n = n / 2;
count++;
}
return count;
}
/* 对数阶（递归实现） */
int logRecur(float n) {
if (n <= 1) return 0;
return logRecur(n / 2) + 1;
}
/* 线性对数阶 */
int linearLogRecur(float n) {
if (n <= 1) return 1;
int count = linearLogRecur(n / 2) +
linearLogRecur(n / 2);
for (int i = 0; i < n; i++) {
count ++;
}
return count;
}
/* 阶乘阶（递归实现） */
int factorialRecur(int n) {
if (n == 0) return 1;
int count = 0;
for (int i = 0; i < n; i++) {
count += factorialRecur(n - 1);
}
return count;
}
/* Driver Code */
int main(int argc, char *argv[]) {
// 可以修改 n 运行，体会一下各种复杂度的操作数量变化趋势
int n = 8;
printf("输入数据大小 n = %d\n", n);
int count = constant(n);
printf("常数阶的计算操作数量 = %d\n", count);
count = linear(n);
printf("线性阶的计算操作数量 = %d\n", count);
// 分配堆区内存（创建一维可变长数组：数组中元素数量为n，元素类型为int）
int *nums = (int *)malloc(n * sizeof(int));
count = arrayTraversal(nums, n);
printf("线性阶（遍历数组）的计算操作数量 = %d\n", count);
count = quadratic(n);
printf("平方阶的计算操作数量 = %d\n", count);
for (int i = 0; i < n; i++) {
nums[i] = n - i; // [n,n-1,...,2,1]
}
count = bubbleSort(nums, n);
printf("平方阶（冒泡排序）的计算操作数量 = %d\n", count);
count = exponential(n);
printf("指数阶（循环实现）的计算操作数量 = %d\n", count);
count = expRecur(n);
printf("指数阶（递归实现）的计算操作数量 = %d\n", count);
count = logarithmic(n);
printf("对数阶（循环实现）的计算操作数量 = %d\n", count);
count = logRecur(n);
printf("对数阶（递归实现）的计算操作数量 = %d\n", count);
count = linearLogRecur(n);
printf("线性对数阶（递归实现）的计算操作数量 = %d\n", count);
count = factorialRecur(n);
printf("阶乘阶（递归实现）的计算操作数量 = %d\n", count);
// 释放堆区内存
if (nums != NULL) {
free(nums);
nums = NULL;
}
getchar();
return 0;
}

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codes/c/chapter_computational_complexity/worst_best_time_complexity.c Normal file
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/**
* File: worst_best_time_complexity.c
* Created Time: 2023-01-03
* Author: sjinzh (sjinzh@gmail.com)
*/
#include "../include/include.h"
/* 生成一个数组，元素为 { 1, 2, ..., n }，顺序被打乱 */
int *randomNumbers(int n) {
// 分配堆区内存（创建一维可变长数组：数组中元素数量为n，元素类型为int）
int *nums = (int *)malloc(n * sizeof(int));
// 生成数组 nums = { 1, 2, 3, ..., n }
for (int i = 0; i < n; i++) {
nums[i] = i + 1;
}
// 随机打乱数组元素
for (int i = n - 1; i > 0; i--) {
int j = rand() % (i + 1);
int temp = nums[i];
nums[i] = nums[j];
nums[j] = temp;
}
return nums;
}
/* 查找数组 nums 中数字 1 所在索引 */
int findOne(int *nums, int n) {
for (int i = 0; i < n; i++) {
if (nums[i] == 1) return i;
}
return -1;
}
/* Driver Code */
int main(int argc, char *argv[]) {
// 初始化随机数种子
srand((unsigned int)time(NULL));
for (int i = 0; i < 10; i++) {
int n = 100;
int *nums = randomNumbers(n);
int index = findOne(nums, n);
printf("\n数组 [ 1, 2, ..., n ] 被打乱后 = ");
PrintArray(nums, n);
printf("数字 1 的索引为 %d\n", index);
// 释放堆区内存
if (nums != NULL) {
free(nums);
nums = NULL;
}
}
return 0;
}

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codes/c/chapter_sorting/CMakeLists.txt Normal file
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add_executable(bubble_sort bubble_sort.c)
add_executable(insertion_sort insertion_sort.c)

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codes/c/chapter_sorting/bubble_sort.c Normal file
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/**
* File: bubble_sort.c
* Created Time: 2022-12-26
* Author: Listening (https://github.com/L-Super)
*/
#include "../include/include.h"
/* 冒泡排序 */
void bubble_sort(int nums[], int size) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (int i = 0; i < size - 1; i++)
{
// 内循环：冒泡操作
for (int j = 0; j < size - 1 - i; j++)
{
if (nums[j] > nums[j + 1])
{
int temp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = temp;
}
}
}
}
/* 冒泡排序（标志优化）*/
void bubble_sort_with_flag(int nums[], int size) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (int i = 0; i < size - 1; i++)
{
bool flag = false;
// 内循环：冒泡操作
for (int j = 0; j < size - 1 - i; j++)
{
if (nums[j] > nums[j + 1])
{
int temp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = temp;
flag = true;
}
}
if (!flag)
break;
}
}
/* Driver Code */
int main() {
int nums[6] = {4, 1, 3, 1, 5, 2};
printf("冒泡排序后: ");
bubble_sort(nums, 6);
for (int i = 0; i < 6; i++)
{
printf("%d ", nums[i]);
}
printf("\n优化版冒泡排序后: ");
bubble_sort_with_flag(nums, 6);
for (int i = 0; i < 6; i++)
{
printf("%d ", nums[i]);
}
printf("\n");
return 0;
}

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/**
* File: insertion_sort.c
* Created Time: 2022-12-29
* Author: Listening (https://github.com/L-Super)
*/
#include "../include/include.h"
/* 插入排序 */
void insertionSort(int nums[], int size) {
// 外循环：base = nums[1], nums[2], ..., nums[n-1]
for (int i = 1; i < size; i++)
{
int base = nums[i], j = i - 1;
// 内循环：将 base 插入到左边的正确位置
while (j >= 0 && nums[j] > base)
{
// 1. 将 nums[j] 向右移动一位
nums[j + 1] = nums[j];
j--;
}
// 2. 将 base 赋值到正确位置
nums[j + 1] = base;
}
}
/* Driver Code */
int main() {
int nums[] = {4, 1, 3, 1, 5, 2};
insertionSort(nums, 6);
printf("插入排序完成后 nums = ");
for (int i = 0; i < 6; i++)
{
printf("%d ", nums[i]);
}
printf("\n");
return 0;
}

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add_executable(binary_search binary_tree.c)
add_executable(binary_tree_bfs binary_tree_bfs.c)
add_executable(binary_tree_dfs binary_tree_dfs.c)
add_executable(binary_search_tree binary_search_tree.c)

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codes/c/chapter_tree/binary_search_tree.c Normal file
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/**
* File: binary_search_tree.c
* Created Time: 2023-01-11
* Author: Reanon (793584285@qq.com)
*/
#include "../include/include.h"

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codes/c/chapter_tree/binary_tree.c Normal file
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/**
* File: binary_tree.c
* Created Time: 2023-01-11
* Author: Reanon (793584285@qq.com)
*/
#include "../include/include.h"
/* Driver Code */
int main() {
/* 初始化二叉树 */
// 初始化结点
TreeNode* n1 = NewTreeNode(1);
TreeNode* n2 = NewTreeNode(2);
TreeNode* n3 = NewTreeNode(3);
TreeNode* n4 = NewTreeNode(4);
TreeNode* n5 = NewTreeNode(5);
// 构建引用指向（即指针）
n1->left = n2;
n1->right = n3;
n2->left = n4;
n2->right = n5;
printf("初始化二叉树\n");
PrintTree(n1);
/* 插入与删除结点 */
TreeNode* P = NewTreeNode(0);
// 在 n1 -> n2 中间插入结点 P
n1->left = P;
P->left = n2;
printf("插入结点 P 后\n");
PrintTree(n1);
// 删除结点 P
n1->left = n2;
// 释放内存
free(P);
printf("删除结点 P 后\n");
PrintTree(n1);
return 0;
}

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codes/c/chapter_tree/binary_tree_bfs.c Normal file
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/**
* File: binary_tree_bfs.c
* Created Time: 2023-01-11
* Author: Reanon (793584285@qq.com)
*/
#include "../include/include.h"
/* 层序遍历 */
int *levelOrder(TreeNode *root, int *size) {
/* 辅助队列 */
int front, rear;
int index, *arr;
TreeNode *node;
TreeNode **queue;
/* 辅助队列 */
queue = (TreeNode **) malloc(sizeof(TreeNode) * MAX_NODE_SIZE);
// 队列指针
front = 0, rear = 0;
// 加入根结点
queue[rear++] = root;
// 初始化一个列表，用于保存遍历序列
/* 辅助数组 */
arr = (int *) malloc(sizeof(int) * MAX_NODE_SIZE);
// 数组指针
index = 0;
while (front < rear) {
// 队列出队
node = queue[front++];
// 保存结点
arr[index++] = node->val;
if (node->left != NULL) {
// 左子结点入队
queue[rear++] = node->left;
}
if (node->right != NULL) {
// 右子结点入队
queue[rear++] = node->right;
}
}
// 更新数组长度的值
*size = index;
arr = realloc(arr, sizeof(int) * (*size));
return arr;
}
/* Driver Code */
int main() {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
int nums[] = {1, 2, 3, NIL, 5, 6, NIL};
int size = sizeof(nums) / sizeof(int);
TreeNode *root = ArrayToTree(nums, size);
printf("初始化二叉树\n");
PrintTree(root);
/* 层序遍历 */
// 需要传入数组的长度
int *arr = levelOrder(root, &size);
printf("层序遍历的结点打印序列 = ");
PrintArray(arr, size);
return 0;
}

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codes/c/chapter_tree/binary_tree_dfs.c Normal file
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/**
* File: binary_tree_dfs.c
* Created Time: 2023-01-11
* Author: Reanon (793584285@qq.com)
*/
#include "../include/include.h"
/* 辅助数组，用于存储遍历序列 */
int *arr;
/* 前序遍历 */
void preOrder(TreeNode *root, int *size) {
if (root == NULL) return;
// 访问优先级：根结点 -> 左子树 -> 右子树
arr[(*size)++] = root->val;
preOrder(root->left, size);
preOrder(root->right, size);
}
/* 中序遍历 */
void inOrder(TreeNode *root, int *size) {
if (root == NULL) return;
// 访问优先级：左子树 -> 根结点 -> 右子树
inOrder(root->left, size);
arr[(*size)++] = root->val;
inOrder(root->right, size);
}
/* 后序遍历 */
void postOrder(TreeNode *root, int *size) {
if (root == NULL) return;
// 访问优先级：左子树 -> 右子树 -> 根结点
postOrder(root->left, size);
postOrder(root->right, size);
arr[(*size)++] = root->val;
}
/* Driver Code */
int main() {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
int nums[] = {1, 2, 3, 4, 5, 6, 7};
int size = sizeof(nums) / sizt ceof(int);
TreeNode *root = ArrayToTree(nums, size);
printf("初始化二叉树\n");
PrintTree(root);
/* 前序遍历 */
// 初始化辅助数组
arr = (int *) malloc(sizeof(int) * MAX_NODE_SIZE);
size = 0;
preOrder(root, &size);
printf("前序遍历的结点打印序列 = ");
PrintArray(arr, size);
/* 中序遍历 */
size = 0;
inOrder(root, &size);
printf("中序遍历的结点打印序列 = ");
PrintArray(arr, size);
/* 后序遍历 */
size = 0;
postOrder(root, &size);
printf("后序遍历的结点打印序列 = ");
PrintArray(arr, size);
return 0;
}

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codes/c/include/CMakeLists.txt Normal file
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add_executable(include
include_test.c
include.h print_util.h
list_node.h tree_node.h)

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/**
* File: include.h
* Created Time: 2022-12-20
* Author: MolDuM (moldum@163.com)、Reanon (793584285@qq.com)
*/
#ifndef C_INCLUDE_H
#define C_INCLUDE_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <time.h>
#include "list_node.h"
#include "tree_node.h"
#include "print_util.h"
#ifdef __cplusplus
extern "C" {
#endif
#ifdef __cplusplus
}
#endif
#endif // C_INCLUDE_H

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codes/c/include/include_test.c Normal file
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/**
* File: include_test.c
* Created Time: 2023-01-10
* Author: Reanon (793584285@qq.com)
*/
#include "include.h"
void testListNode() {
int nums[] = {2, 3, 5, 6, 7};
int size = sizeof(nums) / sizeof(int);
ListNode *head = ArrayToLinkedList(nums, size);
PrintLinkedList(head);
ListNode *node = GetListNode(head, 5);
printf("find node: %d\n", node->val);
}
void testTreeNode() {
int nums[] = {1, 2, 3, NIL, 5, 6, NIL};
int size = sizeof(nums) / sizeof(int);
TreeNode *root = ArrayToTree(nums, size);
// print tree
PrintTree(root);
// tree to arr
int *arr = TreeToArray(root);
PrintArray(arr, size);
}
int main(int argc, char *argv[]) {
printf("==testListNode==\n");
testListNode();
printf("==testTreeNode==\n");
testTreeNode();
return 0;
}

72
codes/c/include/list_node.h Normal file
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@ -0,0 +1,72 @@
/**
* File: list_node.h
* Created Time: 2023-01-09
* Author: Reanon (793584285@qq.com)
*/
#ifndef LIST_NODE_H
#define LIST_NODE_H
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Definition for a singly-linked list node
*
*/
struct ListNode {
int val; // 结点值
struct ListNode *next; // 指向下一结点的指针（引用）
};
// typedef 为 C 语言的关键字，作用是为一种数据类型定义一个新名字
typedef struct ListNode ListNode;
ListNode *NewListNode(int val) {
ListNode *node, *next;
node = (ListNode *) malloc(sizeof(ListNode));
node->val = val;
node->next = NULL;
return node;
}
/**
* @brief Generate a linked list with a vector
*
* @param list
* @return ListNode*
*/
ListNode *ArrayToLinkedList(const int *arr, size_t size) {
if (size <= 0) {
return NULL;
}
ListNode *dummy = NewListNode(0);
ListNode *node = dummy;
for (int i = 0; i < size; i++) {
node->next = NewListNode(arr[i]);
node = node->next;
}
return dummy->next;
}
/**
* @brief Get a list node with specific value from a linked list
*
* @param head
* @param val
* @return ListNode*
*/
ListNode *GetListNode(ListNode *head, int val) {
while (head != NULL && head->val != val) {
head = head->next;
}
return head;
}
#ifdef __cplusplus
}
#endif
#endif // LIST_NODE_H

135
codes/c/include/print_util.h Normal file
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@ -0,0 +1,135 @@
/**
* File: print_util.h
* Created Time: 2022-12-21
* Author: MolDum (moldum@163.com)、Reanon (793584285@qq.com)
*/
#ifndef PRINT_UTIL_H
#define PRINT_UTIL_H
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "list_node.h"
#include "tree_node.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Print an Array
*
* @param arr
* @param size
*/
static void PrintArray(int *arr, int size) {
printf("[");
for (int i = 0; i < size - 1; i++) {
if (arr[i] != NIL) {
printf("%d, ", arr[i]);
} else {
printf("NULL, ");
}
}
if (arr[size - 1] != NIL) {
printf("%d]\n", arr[size - 1]);
}else{
printf("NULL]\n");
}
}
/**
* @brief Print a linked list
*
* @param head
*/
static void PrintLinkedList(ListNode *node) {
if (node == NULL) {
return;
}
while (node->next != NULL) {
printf("%d -> ", node->val);
node = node->next;
}
printf("%d\n", node->val);
}
struct Trunk {
struct Trunk *prev;
char *str;
};
typedef struct Trunk Trunk;
Trunk *newTrunk(Trunk *prev, char *str) {
Trunk *trunk = (Trunk *) malloc(sizeof(Trunk));
trunk->prev = prev;
trunk->str = (char *) malloc(sizeof(char) * 10);
strcpy(trunk->str, str);
return trunk;
}
/**
* @brief Helper function to print branches of the binary tree
*
* @param trunk
*/
void showTrunks(Trunk *trunk) {
if (trunk == NULL) {
return;
}
showTrunks(trunk->prev);
printf("%s", trunk->str);
}
/**
* Help to print a binary tree, hide more details
* @param node
* @param prev
* @param isLeft
*/
static void printTreeHelper(TreeNode *node, Trunk *prev, bool isLeft) {
if (node == NULL) {
return;
}
char *prev_str = " ";
Trunk *trunk = newTrunk(prev, prev_str);
printTreeHelper(node->right, trunk, true);
if (prev == NULL) {
trunk->str = "———";
} else if (isLeft) {
trunk->str = "/———";
prev_str = " |";
} else {
trunk->str = "\\———";
prev->str = prev_str;
}
showTrunks(trunk);
printf("%d\n", node->val);
if (prev != NULL) {
prev->str = prev_str;
}
trunk->str = " |";
printTreeHelper(node->left, trunk, false);
}
/**
* @brief Print a binary tree
*
* @param head
*/
static void PrintTree(TreeNode *root) {
printTreeHelper(root, NULL, false);
}
#ifdef __cplusplus
}
#endif
#endif // PRINT_UTIL_H

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codes/c/include/tree_node.h Normal file
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@ -0,0 +1,131 @@
/**
* File: tree_node.h
* Created Time: 2023-01-09
* Author: Reanon (793584285@qq.com)
*/
#ifndef TREE_NODE_H
#define TREE_NODE_H
#ifdef __cplusplus
extern "C" {
#endif
#define NIL ('#')
#define MAX_NODE_SIZE 5000
struct TreeNode {
int val;
int height;
struct TreeNode *left;
struct TreeNode *right;
};
typedef struct TreeNode TreeNode;
TreeNode *NewTreeNode(int val) {
TreeNode *node;
node = (TreeNode *) malloc(sizeof(TreeNode));
node->val = val;
node->height = 0;
node->left = NULL;
node->right = NULL;
return node;
}
/**
* @brief Generate a binary tree with an array
*
* @param arr
* @param size
* @return TreeNode *
*/
TreeNode *ArrayToTree(const int *arr, size_t size) {
if (size <= 0) {
return NULL;
}
int front, rear, index;
TreeNode *root, *node;
TreeNode **queue;
/* 根结点 */
root = NewTreeNode(arr[0]);
/* 辅助队列 */
queue = (TreeNode **) malloc(sizeof(TreeNode) * MAX_NODE_SIZE);
// 队列指针
front = 0, rear = 0;
// 将根结点放入队尾
queue[rear++] = root;
// 记录遍历数组的索引
index = 0;
while (front < rear) {
// 取队列中的头结点，并让头结点出队
node = queue[front++];
index++;
if (index < size) {
if (arr[index] != NIL) {
node->left = NewTreeNode(arr[index]);
queue[rear++] = node->left;
}
}
index++;
if (index < size) {
if (arr[index] != NIL) {
node->right = NewTreeNode(arr[index]);
queue[rear++] = node->right;
}
}
}
return root;
}
/**
* @brief Generate a binary tree with an array
*
* @param arr
* @param size
* @return TreeNode *
*/
int *TreeToArray(TreeNode *root) {
if (root == NULL) {
return NULL;
}
int front, rear;
int index, *arr;
TreeNode *node;
TreeNode **queue;
/* 辅助队列 */
queue = (TreeNode **) malloc(sizeof(TreeNode) * MAX_NODE_SIZE);
// 队列指针
front = 0, rear = 0;
// 将根结点放入队尾
queue[rear++] = root;
/* 辅助数组 */
arr = (int *) malloc(sizeof(int) * MAX_NODE_SIZE);
// 数组指针
index = 0;
while (front < rear) {
// 取队列中的头结点，并让头结点出队
node = queue[front++];
if (node != NULL) {
arr[index] = node->val;
queue[rear++] = node->left;
queue[rear++] = node->right;
} else {
arr[index] = NIL;
}
index++;
}
return arr;
}
#ifdef __cplusplus
}
#endif
#endif // TREE_NODE_H

2
codes/cpp/chapter_array_and_linkedlist/array.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: array.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

6
codes/cpp/chapter_array_and_linkedlist/linked_list.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: linked_list.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -21,14 +21,16 @@ void remove(ListNode* n0) {
ListNode* P = n0->next;
ListNode* n1 = P->next;
n0->next = n1;
// 释放内存
delete P;
}
/* 访问链表中索引为 index 的结点 */
ListNode* access(ListNode* head, int index) {
for (int i = 0; i < index; i++) {
head = head->next;
if (head == nullptr)
return nullptr;
head = head->next;
}
return head;
}

2
codes/cpp/chapter_array_and_linkedlist/list.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: list.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

2
codes/cpp/chapter_array_and_linkedlist/my_list.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: my_list.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

2
codes/cpp/chapter_computational_complexity/leetcode_two_sum.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: leetcode_two_sum.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

2
codes/cpp/chapter_computational_complexity/space_complexity.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: space_complexity.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

2
codes/cpp/chapter_computational_complexity/time_complexity.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: time_complexity.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

2
codes/cpp/chapter_computational_complexity/worst_best_time_complexity.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: worst_best_time_complexity.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

2
codes/cpp/chapter_hashing/array_hash_map.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: array_hash_map.cpp
* Created Time: 2022-12-14
* Author: msk397 (machangxinq@gmail.com)

2
codes/cpp/chapter_hashing/hash_map.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: hash_map.cpp
* Created Time: 2022-12-14
* Author: msk397 (machangxinq@gmail.com)

2
codes/cpp/chapter_searching/binary_search.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: binary_search.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

2
codes/cpp/chapter_searching/hashing_search.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: hashing_search.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

2
codes/cpp/chapter_searching/linear_search.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: linear_search.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

12
codes/cpp/chapter_sorting/bubble_sort.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: bubble_sort.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -14,9 +14,8 @@ void bubbleSort(vector<int>& nums) {
for (int j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
int tmp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = tmp;
// 这里使用了 std::swap() 函数
swap(nums[j], nums[j + 1]);
}
}
}
@ -31,9 +30,8 @@ void bubbleSortWithFlag(vector<int>& nums) {
for (int j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
int tmp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = tmp;
// 这里使用了 std::swap() 函数
swap(nums[j], nums[j + 1]);
flag = true; // 记录交换元素
}
}

2
codes/cpp/chapter_sorting/insertion_sort.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: insertion_sort.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

6
codes/cpp/chapter_sorting/merge_sort.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: merge_sort.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -25,10 +25,10 @@ void merge(vector<int>& nums, int left, int mid, int right) {
// 若“左子数组已全部合并完”，则选取右子数组元素，并且 j++
if (i > leftEnd)
nums[k] = tmp[j++];
// 否则，若“右子数组已全部合并完”或“左子数组元素 < 右子数组元素”，则选取左子数组元素，并且 i++
// 否则，若“右子数组已全部合并完”或“左子数组元素 <= 右子数组元素”，则选取左子数组元素，并且 i++
else if (j > rightEnd || tmp[i] <= tmp[j])
nums[k] = tmp[i++];
// 否则，若“左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
// 否则，若“左右子数组都未全部合并完”且“左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
else
nums[k] = tmp[j++];
}

2
codes/cpp/chapter_sorting/quick_sort.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: quick_sort.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

9
codes/cpp/chapter_stack_and_queue/array_queue.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: array_queue.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -50,11 +50,10 @@ public:
}
/* 出队 */
int poll() {
void poll() {
int num = peek();
// 队头指针向后移动一位，若越过尾部则返回到数组头部
front = (front + 1) % capacity();
return num;
}
/* 访问队首元素 */
@ -98,8 +97,8 @@ int main() {
cout << "队首元素 peek = " << peek << endl;
/* 元素出队 */
int poll = queue->poll();
cout << "出队元素 poll = " << poll << "，出队后 queue = ";
queue->poll();
cout << "出队元素 poll = " << peek << "，出队后 queue = ";
PrintUtil::printVector(queue->toVector());
/* 获取队列的长度 */

9
codes/cpp/chapter_stack_and_queue/array_stack.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: array_stack.cpp
* Created Time: 2022-11-28
* Author: qualifier1024 (2539244001@qq.com)
@ -28,10 +28,9 @@ public:
}
/* 出栈 */
int pop() {
void pop() {
int oldTop = top();
stack.pop_back();
return oldTop;
}
/* 访问栈顶元素 */
@ -67,8 +66,8 @@ int main() {
cout << "栈顶元素 top = " << top << endl;
/* 元素出栈 */
int pop = stack->pop();
cout << "出栈元素 pop = " << pop << "，出栈后 stack = ";
stack->pop();
cout << "出栈元素 pop = " << top << "，出栈后 stack = ";
PrintUtil::printVector(stack->toVector());
/* 获取栈的长度 */

2
codes/cpp/chapter_stack_and_queue/deque.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: deque.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

12
codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: linkedlist_queue.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -47,12 +47,14 @@ public:
}
/* 出队 */
int poll() {
void poll() {
int num = peek();
// 删除头结点
ListNode *tmp = front;
front = front->next;
// 释放内存
delete tmp;
queSize--;
return num;
}
/* 访问队首元素 */
@ -94,8 +96,8 @@ int main() {
cout << "队首元素 peek = " << peek << endl;
/* 元素出队 */
int poll = queue->poll();
cout << "出队元素 poll = " << poll << "，出队后 queue = ";
queue->poll();
cout << "出队元素 poll = " << peek << "，出队后 queue = ";
PrintUtil::printVector(queue->toVector());
/* 获取队列的长度 */

12
codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: linkedlist_stack.cpp
* Created Time: 2022-11-28
* Author: qualifier1024 (2539244001@qq.com)
@ -37,11 +37,13 @@ public:
}
/* 出栈 */
int pop() {
void pop() {
int num = top();
ListNode *tmp = stackTop;
stackTop = stackTop->next;
// 释放内存
delete tmp;
stkSize--;
return num;
}
/* 访问栈顶元素 */
@ -83,8 +85,8 @@ int main() {
cout << "栈顶元素 top = " << top << endl;
/* 元素出栈 */
int pop = stack->pop();
cout << "出栈元素 pop = " << pop << "，出栈后 stack = ";
stack->pop();
cout << "出栈元素 pop = " << top << "，出栈后 stack = ";
PrintUtil::printVector(stack->toVector());
/* 获取栈的长度 */

2
codes/cpp/chapter_stack_and_queue/queue.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: queue.cpp
* Created Time: 2022-11-28
* Author: qualifier1024 (2539244001@qq.com)

2
codes/cpp/chapter_stack_and_queue/stack.cpp
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@ -1,4 +1,4 @@
/*
/**
* File: stack.cpp
* Created Time: 2022-11-28
* Author: qualifier1024 (2539244001@qq.com)

228
codes/cpp/chapter_tree/avl_tree.cpp
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@ -1,228 +0,0 @@
/*
* File: avl_tree.cpp
* Created Time: 2022-12-2
* Author: mgisr (maguagua0706@gmail.com)
*/
#include "../include/include.hpp"
class AvlTree {
private:
TreeNode *root{};
static bool isBalance(const TreeNode *p);
static int getBalanceFactor(const TreeNode *p);
static void updateHeight(TreeNode *p);
void fixBalance(TreeNode *p);
static bool isLeftChild(const TreeNode *p);
static TreeNode *&fromParentTo(TreeNode *node);
public:
AvlTree() = default;
AvlTree(const AvlTree &p) = default;
const TreeNode *search(int val);
bool insert(int val);
bool remove(int val);
void printTree();
};
// 判断该结点是否平衡
bool AvlTree::isBalance(const TreeNode *p) {
int balance_factor = getBalanceFactor(p);
if (-1 <= balance_factor && balance_factor <= 1) { return true; }
else { return false; }
}
// 获取当前结点的平衡因子
int AvlTree::getBalanceFactor(const TreeNode *p) {
if (p->left == nullptr && p->right == nullptr) { return 0; }
else if (p->left == nullptr) { return (-1 - p->right->height); }
else if (p->right == nullptr) { return p->left->height + 1; }
else { return p->left->height - p->right->height; }
}
// 更新结点高度
void AvlTree::updateHeight(TreeNode *p) {
if (p->left == nullptr && p->right == nullptr) { p->height = 0; }
else if (p->left == nullptr) { p->height = p->right->height + 1; }
else if (p->right == nullptr) { p->height = p->left->height + 1; }
else { p->height = std::max(p->left->height, p->right->height) + 1; }
}
void AvlTree::fixBalance(TreeNode *p) {
// 左旋操作
auto rotate_left = [&](TreeNode *node) -> TreeNode * {
TreeNode *temp = node->right;
temp->parent = p->parent;
node->right = temp->left;
if (temp->left != nullptr) {
temp->left->parent = node;
}
temp->left = node;
node->parent = temp;
updateHeight(node);
updateHeight(temp);
return temp;
};
// 右旋操作
auto rotate_right = [&](TreeNode *node) -> TreeNode * {
TreeNode *temp = node->left;
temp->parent = p->parent;
node->left = temp->right;
if (temp->right != nullptr) {
temp->right->parent = node;
}
temp->right = node;
node->parent = temp;
updateHeight(node);
updateHeight(temp);
return temp;
};
// 根据规则选取旋转方式
if (getBalanceFactor(p) > 1) {
if (getBalanceFactor(p->left) > 0) {
if (p->parent == nullptr) { root = rotate_right(p); }
else { fromParentTo(p) = rotate_right(p); }
} else {
p->left = rotate_left(p->left);
if (p->parent == nullptr) { root = rotate_right(p); }
else { fromParentTo(p) = rotate_right(p); }
}
} else {
if (getBalanceFactor(p->right) < 0) {
if (p->parent == nullptr) { root = rotate_left(p); }
else { fromParentTo(p) = rotate_left(p); }
} else {
p->right = rotate_right(p->right);
if (p->parent == nullptr) { root = rotate_left(p); }
else { fromParentTo(p) = rotate_left(p); }
}
}
}
// 判断当前结点是否为其父节点的左孩子
bool AvlTree::isLeftChild(const TreeNode *p) {
if (p->parent == nullptr) { return false; }
return (p->parent->left == p);
}
// 返回父节点指向当前结点指针的引用
TreeNode *&AvlTree::fromParentTo(TreeNode *node) {
if (isLeftChild(node)) { return node->parent->left; }
else { return node->parent->right; }
}
const TreeNode *AvlTree::search(int val) {
TreeNode *p = root;
while (p != nullptr) {
if (p->val == val) { return p; }
else if (p->val > val) { p = p->left; }
else { p = p->right; }
}
return nullptr;
}
bool AvlTree::insert(int val) {
TreeNode *p = root;
if (p == nullptr) {
root = new TreeNode(val);
return true;
}
for (;;) {
if (p->val == val) { return false; }
else if (p->val > val) {
if (p->left == nullptr) {
p->left = new TreeNode(val, p);
break;
} else {
p = p->left;
}
} else {
if (p->right == nullptr) {
p->right = new TreeNode(val, p);
break;
} else {
p = p->right;
}
}
}
for (; p != nullptr; p = p->parent) {
if (!isBalance(p)) {
fixBalance(p);
break;
} else { updateHeight(p); }
}
return true;
}
bool AvlTree::remove(int val) {
TreeNode *p = root;
if (p == nullptr) { return false; }
while (p != nullptr) {
if (p->val == val) {
TreeNode *real_delete_node = p;
TreeNode *next_node;
if (p->left == nullptr) {
next_node = p->right;
if (p->parent == nullptr) { root = next_node; }
else { fromParentTo(p) = next_node; }
} else if (p->right == nullptr) {
next_node = p->left;
if (p->parent == nullptr) { root = next_node; }
else { fromParentTo(p) = next_node; }
} else {
while (real_delete_node->left != nullptr) {
real_delete_node = real_delete_node->left;
}
std::swap(p->val, real_delete_node->val);
next_node = real_delete_node->right;
if (real_delete_node->parent == p) { p->right = next_node; }
else { real_delete_node->parent->left = next_node; }
}
if (next_node != nullptr) {
next_node->parent = real_delete_node->parent;
}
for (p = real_delete_node; p != nullptr; p = p->parent) {
if (!isBalance(p)) { fixBalance(p); }
updateHeight(p);
}
delete real_delete_node;
return true;
} else if (p->val > val) {
p = p->left;
} else {
p = p->right;
}
}
return false;
}
void inOrder(const TreeNode *root) {
if (root == nullptr) return;
inOrder(root->left);
cout << root->val << ' ';
inOrder(root->right);
}
void AvlTree::printTree() {
inOrder(root);
cout << endl;
}
int main() {
AvlTree tree = AvlTree();
// tree.insert(13);
// tree.insert(24);
// tree.insert(37);
// tree.insert(90);
// tree.insert(53);
tree.insert(53);
tree.insert(90);
tree.insert(37);
tree.insert(24);
tree.insert(13);
tree.remove(90);
tree.printTree();
const TreeNode *p = tree.search(37);
cout << p->val;
return 0;
}

12
codes/cpp/chapter_tree/binary_search_tree.cpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: binary_search_tree.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -96,11 +96,13 @@ public:
// 删除结点 cur
if (pre->left == cur) pre->left = child;
else pre->right = child;
// 释放内存
delete cur;
}
// 子结点数量 = 2
else {
// 获取中序遍历中 cur 的下一个结点
TreeNode* nex = min(cur->right);
TreeNode* nex = getInOrderNext(cur->right);
int tmp = nex->val;
// 递归删除结点 nex
remove(nex->val);
@ -110,8 +112,8 @@ public:
return cur;
}
/* 获取最小结点 */
TreeNode* min(TreeNode* root) {
/* 获取中序遍历中的下一个结点（仅适用于 root 有左子结点的情况） */
TreeNode* getInOrderNext(TreeNode* root) {
if (root == nullptr) return root;
// 循环访问左子结点，直到叶结点时为最小结点，跳出
while (root->left != nullptr) {
@ -131,7 +133,7 @@ int main() {
PrintUtil::printTree(bst->getRoot());
/* 查找结点 */
TreeNode* node = bst->search(5);
TreeNode* node = bst->search(7);
cout << endl << "查找到的结点对象为 " << node << "，结点值 = " << node->val << endl;
/* 插入结点 */

3
codes/cpp/chapter_tree/binary_tree.cpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: binary_tree.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -33,6 +33,7 @@ int main() {
PrintUtil::printTree(n1);
// 删除结点 P
n1->left = n2;
delete P; // 释放内存
cout << endl << "删除结点 P 后\n" << endl;
PrintUtil::printTree(n1);

13
codes/cpp/chapter_tree/binary_tree_bfs.cpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: binary_tree_bfs.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -15,12 +15,12 @@ vector<int> hierOrder(TreeNode* root) {
vector<int> vec;
while (!queue.empty()) {
TreeNode* node = queue.front();
queue.pop(); // 队列出队
vec.push_back(node->val); // 保存结点
queue.pop(); // 队列出队
vec.push_back(node->val); // 保存结点
if (node->left != nullptr)
queue.push(node->left); // 左子结点入队
queue.push(node->left); // 左子结点入队
if (node->right != nullptr)
queue.push(node->right); // 右子结点入队
queue.push(node->right); // 右子结点入队
}
return vec;
}
@ -30,8 +30,7 @@ vector<int> hierOrder(TreeNode* root) {
int main() {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
TreeNode* root = vecToTree(vector<int>
{ 1, 2, 3, 4, 5, 6, 7, INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX });
TreeNode* root = vecToTree(vector<int> { 1, 2, 3, 4, 5, 6, 7 });
cout << endl << "初始化二叉树\n" << endl;
PrintUtil::printTree(root);

5
codes/cpp/chapter_tree/binary_tree_dfs.cpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: binary_tree_dfs.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -41,8 +41,7 @@ void postOrder(TreeNode* root) {
int main() {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
TreeNode* root = vecToTree(vector<int>
{ 1, 2, 3, 4, 5, 6, 7, INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX});
TreeNode* root = vecToTree(vector<int> { 1, 2, 3, 4, 5, 6, 7 });
cout << endl << "初始化二叉树\n" << endl;
PrintUtil::printTree(root);

2
codes/cpp/include/ListNode.hpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: PrintUtil.hpp
* Created Time: 2021-12-19
* Author: Krahets (krahets@163.com)

3
codes/cpp/include/PrintUtil.hpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: PrintUtil.hpp
* Created Time: 2021-12-19
* Author: Krahets (krahets@163.com), msk397 (machangxinq@gmail.com)
@ -9,6 +9,7 @@
#include <iostream>
#include <string>
#include <sstream>
#include <climits>
#include "ListNode.hpp"
#include "TreeNode.hpp"

17
codes/cpp/include/TreeNode.hpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: PrintUtil.hpp
* Created Time: 2021-12-19
* Author: Krahets (krahets@163.com)
@ -27,23 +27,24 @@ struct TreeNode {
* @return TreeNode*
*/
TreeNode *vecToTree(vector<int> list) {
if (list.empty()) {
if (list.empty())
return nullptr;
}
auto *root = new TreeNode(list[0]);
queue<TreeNode *> que;
size_t n = list.size(), index = 1;
while (index < n) {
que.emplace(root);
size_t n = list.size(), index = 0;
while (!que.empty()) {
auto node = que.front();
que.pop();
if (++index >= n) break;
if (index < n) {
node->left = new TreeNode(list[index++]);
node->left = new TreeNode(list[index]);
que.emplace(node->left);
}
if (++index >= n) break;
if (index < n) {
node->right = new TreeNode(list[index++]);
node->right = new TreeNode(list[index]);
que.emplace(node->right);
}
}

2
codes/cpp/include/include.hpp
View file

@ -1,4 +1,4 @@
/*
/**
* File: PrintUtil.hpp
* Created Time: 2021-12-19
* Author: Krahets (krahets@163.com)

30
codes/csharp/chapter_array_and_linkedlist/array.cs
View file

@ -8,9 +8,7 @@ namespace hello_algo.chapter_array_and_linkedlist
{
public class Array
{
/// <summary>
/// 随机返回一个数组元素
/// </summary>
/* 随机返回一个数组元素 */
public static int RandomAccess(int[] nums)
{
Random random = new();
@ -19,9 +17,7 @@ namespace hello_algo.chapter_array_and_linkedlist
return randomNum;
}
/// <summary>
/// 扩展数组长度
/// </summary>
/* 扩展数组长度 */
public static int[] Extend(int[] nums, int enlarge)
{
// 初始化一个扩展长度后的数组
@ -35,9 +31,7 @@ namespace hello_algo.chapter_array_and_linkedlist
return res;
}
/// <summary>
/// 在数组的索引 index 处插入元素 num
/// </summary>
/* 在数组的索引 index 处插入元素 num */
public static void Insert(int[] nums, int num, int index)
{
// 把索引 index 以及之后的所有元素向后移动一位
@ -49,9 +43,7 @@ namespace hello_algo.chapter_array_and_linkedlist
nums[index] = num;
}
/// <summary>
/// 删除索引 index 处元素
/// </summary>
/* 删除索引 index 处元素 */
public static void Remove(int[] nums, int index)
{
// 把索引 index 之后的所有元素向前移动一位
@ -61,9 +53,7 @@ namespace hello_algo.chapter_array_and_linkedlist
}
}
/// <summary>
/// 遍历数组
/// </summary>
/* 遍历数组 */
public static void Traverse(int[] nums)
{
int count = 0;
@ -79,9 +69,7 @@ namespace hello_algo.chapter_array_and_linkedlist
}
}
/// <summary>
/// 在数组中查找指定元素
/// </summary>
/* 在数组中查找指定元素 */
public static int Find(int[] nums, int target)
{
for (int i = 0; i < nums.Length; i++)
@ -92,15 +80,13 @@ namespace hello_algo.chapter_array_and_linkedlist
return -1;
}
/// <summary>
/// 辅助函数,数组转字符串
/// </summary>
/* 辅助函数,数组转字符串 */
public static string ToString(int[] nums)
{
return string.Join(",", nums);
}
// Driver Code
[Test]
public static void Test()
{

20
codes/csharp/chapter_array_and_linkedlist/linked_list.cs
View file

@ -9,9 +9,7 @@ namespace hello_algo.chapter_array_and_linkedlist
{
public class linked_list
{
/// <summary>
/// 在链表的结点 n0 之后插入结点 P
/// </summary>
/* 在链表的结点 n0 之后插入结点 P */
public static void Insert(ListNode n0, ListNode P)
{
ListNode? n1 = n0.next;
@ -19,9 +17,7 @@ namespace hello_algo.chapter_array_and_linkedlist
P.next = n1;
}
/// <summary>
/// 删除链表的结点 n0 之后的首个结点
/// </summary>
/* 删除链表的结点 n0 之后的首个结点 */
public static void Remove(ListNode n0)
{
if (n0.next == null)
@ -32,23 +28,19 @@ namespace hello_algo.chapter_array_and_linkedlist
n0.next = n1;
}
/// <summary>
/// 访问链表中索引为 index 的结点
/// </summary>
/* 访问链表中索引为 index 的结点 */
public static ListNode? Access(ListNode head, int index)
{
for (int i = 0; i < index; i++)
{
head = head.next;
if (head == null)
return null;
head = head.next;
}
return head;
}
/// <summary>
/// 在链表中查找值为 target 的首个结点
/// </summary>
/* 在链表中查找值为 target 的首个结点 */
public static int Find(ListNode head, int target)
{
int index = 0;
@ -62,7 +54,7 @@ namespace hello_algo.chapter_array_and_linkedlist
return -1;
}
// Driver Code
[Test]
public void Test()
{

4
codes/csharp/chapter_sorting/merge_sort.cs
View file

@ -31,10 +31,10 @@ namespace hello_algo.chapter_sorting
// 若“左子数组已全部合并完”，则选取右子数组元素，并且 j++
if (i > leftEnd)
nums[k] = tmp[j++];
// 否则，若“右子数组已全部合并完”或“左子数组元素 < 右子数组元素”，则选取左子数组元素，并且 i++
// 否则，若“右子数组已全部合并完”或“左子数组元素 <= 右子数组元素”，则选取左子数组元素，并且 i++
else if (j > rightEnd || tmp[i] <= tmp[j])
nums[k] = tmp[i++];
// 否则，若“左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
// 否则，若“左右子数组都未全部合并完”且“左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
else
nums[k] = tmp[j++];
}

49
codes/csharp/chapter_stack_and_queue/deque.cs Normal file
View file

@ -0,0 +1,49 @@
/**
* File: deque.cs
* Created Time: 2022-12-30
* Author: moonache (microin1301@outlook.com)
*/
using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue
{
public class deque
{
[Test]
public void Test()
{
/* 初始化双向队列 */
// 在 C# 中，将链表 LinkedList 看作双向队列来使用
LinkedList<int> deque = new LinkedList<int>();
/* 元素入队 */
deque.AddLast(2); // 添加至队尾
deque.AddLast(5);
deque.AddLast(4);
deque.AddFirst(3); // 添加至队首
deque.AddFirst(1);
Console.WriteLine("双向队列 deque = " + String.Join(",", deque.ToArray()));
/* 访问元素 */
int peekFirst = deque.First.Value; // 队首元素
Console.WriteLine("队首元素 peekFirst = " + peekFirst);
int peekLast = deque.Last.Value; // 队尾元素
Console.WriteLine("队尾元素 peekLast = " + peekLast);
/* 元素出队 */
deque.RemoveFirst(); // 队首元素出队
Console.WriteLine("队首元素出队后 deque = " + String.Join(",", deque.ToArray()));
deque.RemoveLast(); // 队尾元素出队
Console.WriteLine("队尾元素出队后 deque = " + String.Join(",", deque.ToArray()));
/* 获取双向队列的长度 */
int size = deque.Count;
Console.WriteLine("双向队列长度 size = " + size);
/* 判断双向队列是否为空 */
bool isEmpty = deque.Count == 0;
Console.WriteLine("双向队列是否为空 = " + isEmpty);
}
}
}

6
codes/csharp/chapter_tree/avl_tree.cs
View file

@ -162,7 +162,7 @@ namespace hello_algo.chapter_tree
else
{
// 子结点数量 = 2 ，则将中序遍历的下个结点删除，并用该结点替换当前结点
TreeNode? temp = minNode(node.right);
TreeNode? temp = getInOrderNext(node.right);
node.right = removeHelper(node.right, temp.val);
node.val = temp.val;
}
@ -174,8 +174,8 @@ namespace hello_algo.chapter_tree
return node;
}
/* 获取最小结点 */
private TreeNode? minNode(TreeNode? node)
/* 获取中序遍历中的下一个结点（仅适用于 root 有左子结点的情况） */
private TreeNode? getInOrderNext(TreeNode? node)
{
if (node == null) return node;
// 循环访问左子结点，直到叶结点时为最小结点，跳出

14
codes/csharp/chapter_tree/binary_search_tree.cs
View file

@ -35,11 +35,7 @@ namespace hello_algo.chapter_tree
return root;
}
/// <summary>
/// 查找结点
/// </summary>
/// <param name="num"></param>
/// <returns></returns>
/* 查找结点 */
public TreeNode? search(int num)
{
TreeNode? cur = root;
@ -125,7 +121,7 @@ namespace hello_algo.chapter_tree
else
{
// 获取中序遍历中 cur 的下一个结点
TreeNode? nex = min(cur.right);
TreeNode? nex = getInOrderNext(cur.right);
if (nex != null)
{
int tmp = nex.val;
@ -138,8 +134,8 @@ namespace hello_algo.chapter_tree
return cur;
}
/* 获取最小结点 */
private TreeNode? min(TreeNode? root)
/* 获取中序遍历中的下一个结点（仅适用于 root 有左子结点的情况） */
private TreeNode? getInOrderNext(TreeNode? root)
{
if (root == null) return root;
// 循环访问左子结点，直到叶结点时为最小结点，跳出
@ -163,7 +159,7 @@ namespace hello_algo.chapter_tree
PrintUtil.PrintTree(bst.getRoot());
/* 查找结点 */
TreeNode? node = bst.search(5);
TreeNode? node = bst.search(7);
Console.WriteLine("\n查找到的结点对象为 " + node + "，结点值 = " + node.val);
/* 插入结点 */

9
codes/csharp/chapter_tree/binary_tree_bfs.cs
View file

@ -12,11 +12,7 @@ namespace hello_algo.chapter_tree
public class binary_tree_bfs
{
/// <summary>
/// 层序遍历
/// </summary>
/// <param name="root"></param>
/// <returns></returns>
/* 层序遍历 */
public List<int> hierOrder(TreeNode root)
{
// 初始化队列，加入根结点
@ -41,8 +37,7 @@ namespace hello_algo.chapter_tree
{
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
TreeNode? root = TreeNode.ArrToTree(new int?[] {
1, 2, 3, 4, 5, 6, 7, null, null, null, null, null, null, null, null});
TreeNode? root = TreeNode.ArrToTree(new int?[] { 1, 2, 3, 4, 5, 6, 7 });
Console.WriteLine("\n初始化二叉树\n");
PrintUtil.PrintTree(root);

18
codes/csharp/chapter_tree/binary_tree_dfs.cs
View file

@ -13,10 +13,7 @@ namespace hello_algo.chapter_tree
{
List<int> list = new();
/// <summary>
/// 前序遍历
/// </summary>
/// <param name="root"></param>
/* 前序遍历 */
void preOrder(TreeNode? root)
{
if (root == null) return;
@ -26,10 +23,7 @@ namespace hello_algo.chapter_tree
preOrder(root.right);
}
/// <summary>
/// 中序遍历
/// </summary>
/// <param name="root"></param>
/* 中序遍历 */
void inOrder(TreeNode? root)
{
if (root == null) return;
@ -39,10 +33,7 @@ namespace hello_algo.chapter_tree
inOrder(root.right);
}
/// <summary>
/// 后序遍历
/// </summary>
/// <param name="root"></param>
/* 后序遍历 */
void postOrder(TreeNode? root)
{
if (root == null) return;
@ -57,8 +48,7 @@ namespace hello_algo.chapter_tree
{
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
TreeNode? root = TreeNode.ArrToTree(new int?[] {
1, 2, 3, 4, 5, 6, 7, null, null, null, null, null, null, null, null});
TreeNode? root = TreeNode.ArrToTree(new int?[] { 1, 2, 3, 4, 5, 6, 7 });
Console.WriteLine("\n初始化二叉树\n");
PrintUtil.PrintTree(root);

4
codes/csharp/hello-algo.csproj
View file

@ -11,8 +11,8 @@
<ItemGroup>
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.4.0" />
<PackageReference Include="NUnit" Version="3.13.3" />
<PackageReference Include="NUnit3TestAdapter" Version="4.0.0" />
<PackageReference Include="coverlet.collector" Version="3.1.0" />
<PackageReference Include="NUnit3TestAdapter" Version="4.0.0" />
<PackageReference Include="coverlet.collector" Version="3.1.0" />
</ItemGroup>
</Project>

10
codes/csharp/include/TreeNode.cs
View file

@ -19,7 +19,7 @@ namespace hello_algo.include
}
/**
* Generate a binary tree with an array
* Generate a binary tree given an array
* @param arr
* @return
*/
@ -31,22 +31,22 @@ namespace hello_algo.include
TreeNode root = new TreeNode((int) arr[0]);
Queue<TreeNode> queue = new Queue<TreeNode>();
queue.Enqueue(root);
int i = 1;
while (queue.Count!=0)
int i = 0;
while (queue.Count != 0)
{
TreeNode node = queue.Dequeue();
if (++i >= arr.Length) break;
if (arr[i] != null)
{
node.left = new TreeNode((int) arr[i]);
queue.Enqueue(node.left);
}
i++;
if (++i >= arr.Length) break;
if (arr[i] != null)
{
node.right = new TreeNode((int) arr[i]);
queue.Enqueue(node.right);
}
i++;
}
return root;
}

74
codes/go/chapter_array_and_linkedlist/array.go Normal file
View file

@ -0,0 +1,74 @@
// File: array.go
// Created Time: 2022-12-29
// Author: GuoWei (gongguowei01@gmail.com), cathay (cathaycchen@gmail.com)
package chapter_array_and_linkedlist
import (
"math/rand"
)
/* 随机返回一个数组元素 */
func randomAccess(nums []int) (randomNum int) {
// 在区间 [0, nums.length) 中随机抽取一个数字
randomIndex := rand.Intn(len(nums))
// 获取并返回随机元素
randomNum = nums[randomIndex]
return
}
/* 扩展数组长度 */
func extend(nums []int, enlarge int) []int {
// 初始化一个扩展长度后的数组
res := make([]int, len(nums)+enlarge)
// 将原数组中的所有元素复制到新数组
for i, num := range nums {
res[i] = num
}
// 返回扩展后的新数组
return res
}
/* 在数组的索引 index 处插入元素 num */
func insert(nums []int, num int, index int) {
// 把索引 index 以及之后的所有元素向后移动一位
for i := len(nums) - 1; i > index; i-- {
nums[i] = nums[i-1]
}
// 将 num 赋给 index 处元素
nums[index] = num
}
/* 删除索引 index 处元素 */
func remove(nums []int, index int) {
// 把索引 index 之后的所有元素向前移动一位
for i := index; i < len(nums)-1; i++ {
nums[i] = nums[i+1]
}
}
/* 遍历数组 */
func traverse(nums []int) {
count := 0
// 通过索引遍历数组
for i := 0; i < len(nums); i++ {
count++
}
count = 0
// 直接遍历数组
for range nums {
count++
}
}
/* 在数组中查找指定元素 */
func find(nums []int, target int) (index int) {
index = -1
for i := 0; i < len(nums); i++ {
if nums[i] == target {
index = i
break
}
}
return
}

50
codes/go/chapter_array_and_linkedlist/array_test.go Normal file
View file

@ -0,0 +1,50 @@
// File: array_test.go
// Created Time: 2022-12-29
// Author: GuoWei (gongguowei01@gmail.com), cathay (cathaycchen@gmail.com)
package chapter_array_and_linkedlist
/**
我们将 Go 中的 Slice 切片看作 Array 数组。因为这样可以
降低理解成本，利于我们将关注点放在数据结构与算法上。
*/
import (
"fmt"
"testing"
)
/* Driver Code */
func TestArray(t *testing.T) {
/* 初始化数组 */
var arr [5]int
fmt.Println("数组 arr =", arr)
// 在 Go 中，指定长度时（[5]int）为数组，不指定长度时（[]int）为切片
// 由于 Go 的数组被设计为在编译期确定长度，因此只能使用常量来指定长度
// 为了方便实现扩容 extend() 方法，以下将切片（Slice）看作数组（Array）
nums := []int{1, 3, 2, 5, 4}
fmt.Println("数组 nums =", nums)
/* 随机访问 */
randomNum := randomAccess(nums)
fmt.Println("在 nums 中获取随机元素", randomNum)
/* 长度扩展 */
nums = extend(nums, 3)
fmt.Println("将数组长度扩展至 8 ，得到 nums =", nums)
/* 插入元素 */
insert(nums, 6, 3)
fmt.Println("在索引 3 处插入数字 6 ，得到 nums =", nums)
/* 删除元素 */
remove(nums, 2)
fmt.Println("删除索引 2 处的元素，得到 nums =", nums)
/* 遍历数组 */
traverse(nums)
/* 查找元素 */
index := find(nums, 3)
fmt.Println("在 nums 中查找元素 3 ，得到索引 =", index)
}

51
codes/go/chapter_array_and_linkedlist/linked_list.go Normal file
View file

@ -0,0 +1,51 @@
// File: linked_list.go
// Created Time: 2022-12-29
// Author: cathay (cathaycchen@gmail.com)
package chapter_array_and_linkedlist
import (
. "github.com/krahets/hello-algo/pkg"
)
/* 在链表的结点 n0 之后插入结点 P */
func insertNode(n0 *ListNode, P *ListNode) {
n1 := n0.Next
n0.Next = P
P.Next = n1
}
/* 删除链表的结点 n0 之后的首个结点 */
func removeNode(n0 *ListNode) {
if n0.Next == nil {
return
}
// n0 -> P -> n1
P := n0.Next
n1 := P.Next
n0.Next = n1
}
/* 访问链表中索引为 index 的结点 */
func access(head *ListNode, index int) *ListNode {
for i := 0; i < index; i++ {
if head == nil {
return nil
}
head = head.Next
}
return head
}
/* 在链表中查找值为 target 的首个结点 */
func findNode(head *ListNode, target int) int {
index := 0
for head != nil {
if head.Val == target {
return index
}
head = head.Next
index++
}
return -1
}

48
codes/go/chapter_array_and_linkedlist/linked_list_test.go Normal file
View file

@ -0,0 +1,48 @@
// File: linked_list_test.go
// Created Time: 2022-12-29
// Author: cathay (cathaycchen@gmail.com)
package chapter_array_and_linkedlist
import (
"fmt"
"testing"
. "github.com/krahets/hello-algo/pkg"
)
func TestLikedList(t *testing.T) {
/* 初始化链表 1 -> 3 -> 2 -> 5 -> 4 */
// 初始化各个结点
n0 := NewListNode(1)
n1 := NewListNode(3)
n2 := NewListNode(2)
n3 := NewListNode(5)
n4 := NewListNode(4)
// 构建引用指向
n0.Next = n1
n1.Next = n2
n2.Next = n3
n3.Next = n4
fmt.Println("初始化的链表为")
PrintLinkedList(n0)
/* 插入结点 */
insertNode(n0, NewListNode(0))
fmt.Println("插入结点后的链表为")
PrintLinkedList(n0)
/* 删除结点 */
removeNode(n0)
fmt.Println("删除结点后的链表为")
PrintLinkedList(n0)
/* 访问结点 */
node := access(n0, 3)
fmt.Println("链表中索引 3 处的结点的值 =", node)
/* 查找结点 */
index := findNode(n0, 2)
fmt.Println("链表中值为 2 的结点的索引 =", index)
}

24
codes/go/chapter_array_and_linkedlist/my_list.go
View file

@ -5,7 +5,7 @@
package chapter_array_and_linkedlist
/* 列表类简易实现 */
type MyList struct {
type myList struct {
numsCapacity int
nums []int
numsSize int
@ -13,8 +13,8 @@ type MyList struct {
}
/* 构造函数 */
func newMyList() *MyList {
return &MyList{
func newMyList() *myList {
return &myList{
numsCapacity: 10, // 列表容量
nums: make([]int, 10), // 数组（存储列表元素）
numsSize: 0, // 列表长度（即当前元素数量）
@ -23,17 +23,17 @@ func newMyList() *MyList {
}
/* 获取列表长度（即当前元素数量） */
func (l *MyList) size() int {
func (l *myList) size() int {
return l.numsSize
}
/* 获取列表容量 */
func (l *MyList) capacity() int {
func (l *myList) capacity() int {
return l.numsCapacity
}
/* 访问元素 */
func (l *MyList) get(index int) int {
func (l *myList) get(index int) int {
// 索引如果越界则抛出异常，下同
if index >= l.numsSize {
panic("索引越界")
@ -42,7 +42,7 @@ func (l *MyList) get(index int) int {
}
/* 更新元素 */
func (l *MyList) set(num, index int) {
func (l *myList) set(num, index int) {
if index >= l.numsSize {
panic("索引越界")
}
@ -50,7 +50,7 @@ func (l *MyList) set(num, index int) {
}
/* 尾部添加元素 */
func (l *MyList) add(num int) {
func (l *myList) add(num int) {
// 元素数量超出容量时，触发扩容机制
if l.numsSize == l.numsCapacity {
l.extendCapacity()
@ -61,7 +61,7 @@ func (l *MyList) add(num int) {
}
/* 中间插入元素 */
func (l *MyList) insert(num, index int) {
func (l *myList) insert(num, index int) {
if index >= l.numsSize {
panic("索引越界")
}
@ -79,7 +79,7 @@ func (l *MyList) insert(num, index int) {
}
/* 删除元素 */
func (l *MyList) remove(index int) int {
func (l *myList) remove(index int) int {
if index >= l.numsSize {
panic("索引越界")
}
@ -95,7 +95,7 @@ func (l *MyList) remove(index int) int {
}
/* 列表扩容 */
func (l *MyList) extendCapacity() {
func (l *myList) extendCapacity() {
// 新建一个长度为 self.__size 的数组，并将原数组拷贝到新数组
l.nums = append(l.nums, make([]int, l.numsCapacity*(l.extendRatio-1))...)
// 更新列表容量
@ -103,7 +103,7 @@ func (l *MyList) extendCapacity() {
}
/* 返回有效长度的列表 */
func (l *MyList) toArray() []int {
func (l *myList) toArray() []int {
// 仅转换有效长度范围内的列表元素
return l.nums[:l.numsSize]
}

32
codes/go/chapter_computational_complexity/space_complexity.go
View file

@ -9,31 +9,31 @@ import (
"strconv"
)
/* Node 结构体 */
type Node struct {
/* 结构体 */
type node struct {
val int
next *Node
next *node
}
/* TreeNode 二叉树 */
type TreeNode struct {
/* treeNode 二叉树 */
type treeNode struct {
val int
left *TreeNode
right *TreeNode
left *treeNode
right *treeNode
}
/* 创建 Node 结构体 */
func newNode(val int) *Node {
return &Node{val: val}
/* 创建 node 结构体 */
func newNode(val int) *node {
return &node{val: val}
}
/* 创建 TreeNode 结构体 */
func newTreeNode(val int) *TreeNode {
return &TreeNode{val: val}
/* 创建 treeNode 结构体 */
func newTreeNode(val int) *treeNode {
return &treeNode{val: val}
}
/* 输出二叉树 */
func printTree(root *TreeNode) {
func printTree(root *treeNode) {
if root == nil {
return
}
@ -72,7 +72,7 @@ func spaceLinear(n int) {
// 长度为 n 的数组占用 O(n) 空间
_ = make([]int, n)
// 长度为 n 的列表占用 O(n) 空间
var nodes []*Node
var nodes []*node
for i := 0; i < n; i++ {
nodes = append(nodes, newNode(i))
}
@ -112,7 +112,7 @@ func spaceQuadraticRecur(n int) int {
}
/* 指数阶（建立满二叉树） */
func buildTree(n int) *TreeNode {
func buildTree(n int) *treeNode {
if n == 0 {
return nil
}

32
codes/go/chapter_hashing/array_hash_map.go
View file

@ -7,30 +7,30 @@ package chapter_hashing
import "fmt"
/* 键值对 int->String */
type Entry struct {
type entry struct {
key int
val string
}
/* 基于数组简易实现的哈希表 */
type ArrayHashMap struct {
bucket []*Entry
type arrayHashMap struct {
bucket []*entry
}
func newArrayHashMap() *ArrayHashMap {
func newArrayHashMap() *arrayHashMap {
// 初始化一个长度为 100 的桶（数组）
bucket := make([]*Entry, 100)
return &ArrayHashMap{bucket: bucket}
bucket := make([]*entry, 100)
return &arrayHashMap{bucket: bucket}
}
/* 哈希函数 */
func (a *ArrayHashMap) hashFunc(key int) int {
func (a *arrayHashMap) hashFunc(key int) int {
index := key % 100
return index
}
/* 查询操作 */
func (a *ArrayHashMap) get(key int) string {
func (a *arrayHashMap) get(key int) string {
index := a.hashFunc(key)
pair := a.bucket[index]
if pair == nil {
@ -40,22 +40,22 @@ func (a *ArrayHashMap) get(key int) string {
}
/* 添加操作 */
func (a *ArrayHashMap) put(key int, val string) {
pair := &Entry{key: key, val: val}
func (a *arrayHashMap) put(key int, val string) {
pair := &entry{key: key, val: val}
index := a.hashFunc(key)
a.bucket[index] = pair
}
/* 删除操作 */
func (a *ArrayHashMap) remove(key int) {
func (a *arrayHashMap) remove(key int) {
index := a.hashFunc(key)
// 置为 nil ，代表删除
a.bucket[index] = nil
}
/* 获取所有键对 */
func (a *ArrayHashMap) entrySet() []*Entry {
var pairs []*Entry
func (a *arrayHashMap) entrySet() []*entry {
var pairs []*entry
for _, pair := range a.bucket {
if pair != nil {
pairs = append(pairs, pair)
@ -65,7 +65,7 @@ func (a *ArrayHashMap) entrySet() []*Entry {
}
/* 获取所有键 */
func (a *ArrayHashMap) keySet() []int {
func (a *arrayHashMap) keySet() []int {
var keys []int
for _, pair := range a.bucket {
if pair != nil {
@ -76,7 +76,7 @@ func (a *ArrayHashMap) keySet() []int {
}
/* 获取所有值 */
func (a *ArrayHashMap) valueSet() []string {
func (a *arrayHashMap) valueSet() []string {
var values []string
for _, pair := range a.bucket {
if pair != nil {
@ -87,7 +87,7 @@ func (a *ArrayHashMap) valueSet() []string {
}
/* 打印哈希表 */
func (a *ArrayHashMap) print() {
func (a *arrayHashMap) print() {
for _, pair := range a.bucket {
if pair != nil {
fmt.Println(pair.key, "->", pair.val)

3
codes/go/chapter_searching/hashing_search_test.go
View file

@ -6,8 +6,9 @@ package chapter_searching
import (
"fmt"
. "github.com/krahets/hello-algo/pkg"
"testing"
. "github.com/krahets/hello-algo/pkg"
)
func TestHashingSearch(t *testing.T) {

2
codes/go/chapter_sorting/bubble_sort/bubble_sort.go → codes/go/chapter_sorting/bubble_sort.go
View file

@ -2,7 +2,7 @@
// Created Time: 2022-12-06
// Author: Slone123c (274325721@qq.com)
package bubble_sort
package chapter_sorting
/* 冒泡排序 */
func bubbleSort(nums []int) {

2
codes/go/chapter_sorting/bubble_sort/bubble_sort_test.go → codes/go/chapter_sorting/bubble_sort_test.go
View file

@ -2,7 +2,7 @@
// Created Time: 2022-12-06
// Author: Slone123c (274325721@qq.com)
package bubble_sort
package chapter_sorting
import (
"fmt"

2
codes/go/chapter_sorting/insertion_sort/insertion_sort.go → codes/go/chapter_sorting/insertion_sort.go
View file

@ -2,7 +2,7 @@
// Created Time: 2022-12-12
// Author: msk397 (machangxinq@gmail.com)
package insertion_sort
package chapter_sorting
func insertionSort(nums []int) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1

2
codes/go/chapter_sorting/insertion_sort/insertion_sort_test.go → codes/go/chapter_sorting/insertion_sort_test.go
View file

@ -2,7 +2,7 @@
// Created Time: 2022-12-12
// Author: msk397 (machangxinq@gmail.com)
package insertion_sort
package chapter_sorting
import (
"fmt"

18
codes/go/chapter_sorting/merge_sort/merge_sort.go → codes/go/chapter_sorting/merge_sort.go
View file

@ -2,34 +2,34 @@
// Created Time: 2022-12-13
// Author: msk397 (machangxinq@gmail.com)
package merge_sort
package chapter_sorting
// 合并左子数组和右子数组
// 左子数组区间 [left, mid]
// 右子数组区间 [mid + 1, right]
func merge(nums []int, left, mid, right int) {
// 初始化辅助数组 借助 copy模块
// 初始化辅助数组 借助 copy 模块
tmp := make([]int, right-left+1)
for i := left; i <= right; i++ {
tmp[i-left] = nums[i]
}
// 左子数组的起始索引和结束索引
left_start, left_end := left-left, mid-left
leftStart, leftEnd := left-left, mid-left
// 右子数组的起始索引和结束索引
right_start, right_end := mid+1-left, right-left
rightStart, rightEnd := mid+1-left, right-left
// i, j 分别指向左子数组、右子数组的首元素
i, j := left_start, right_start
i, j := leftStart, rightStart
// 通过覆盖原数组 nums 来合并左子数组和右子数组
for k := left; k <= right; k++ {
// 若“左子数组已全部合并完”，则选取右子数组元素，并且 j++
if i > left_end {
if i > leftEnd {
nums[k] = tmp[j]
j++
// 否则，若“右子数组已全部合并完”或“左子数组元素 < 右子数组元素”，则选取左子数组元素，并且 i++
} else if j > right_end || tmp[i] <= tmp[j] {
// 否则，若“右子数组已全部合并完”或“左子数组元素 <= 右子数组元素”，则选取左子数组元素，并且 i++
} else if j > rightEnd || tmp[i] <= tmp[j] {
nums[k] = tmp[i]
i++
// 否则，若“左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
// 否则，若“左右子数组都未全部合并完”且“左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
} else {
nums[k] = tmp[j]
j++

3
codes/go/chapter_sorting/merge_sort/merge_sort_test.go → codes/go/chapter_sorting/merge_sort_test.go
View file

@ -1,8 +1,9 @@
package merge_sort
// File: merge_sort_test.go
// Created Time: 2022-12-13
// Author: msk397 (machangxinq@gmail.com)
package chapter_sorting
import (
"fmt"
"testing"

22
codes/go/chapter_sorting/quick_sort/quick_sort.go → codes/go/chapter_sorting/quick_sort.go
View file

@ -2,19 +2,19 @@
// Created Time: 2022-12-12
// Author: msk397 (machangxinq@gmail.com)
package quick_sort
package chapter_sorting
// 快速排序
type QuickSort struct{}
type quickSort struct{}
// 快速排序（中位基准数优化）
type QuickSortMedian struct{}
type quickSortMedian struct{}
// 快速排序（尾递归优化）
type QuickSortTailCall struct{}
type quickSortTailCall struct{}
/* 哨兵划分 */
func (q *QuickSort) partition(nums []int, left, right int) int {
func (q *quickSort) partition(nums []int, left, right int) int {
// 以 nums[left] 作为基准数
i, j := left, right
for i < j {
@ -33,7 +33,7 @@ func (q *QuickSort) partition(nums []int, left, right int) int {
}
/* 快速排序 */
func (q *QuickSort) quickSort(nums []int, left, right int) {
func (q *quickSort) quickSort(nums []int, left, right int) {
// 子数组长度为 1 时终止递归
if left >= right {
return
@ -46,7 +46,7 @@ func (q *QuickSort) quickSort(nums []int, left, right int) {
}
/* 选取三个元素的中位数 */
func (q *QuickSortMedian) medianThree(nums []int, left, mid, right int) int {
func (q *quickSortMedian) medianThree(nums []int, left, mid, right int) int {
if (nums[left] > nums[mid]) != (nums[left] > nums[right]) {
return left
} else if (nums[mid] < nums[left]) != (nums[mid] > nums[right]) {
@ -56,7 +56,7 @@ func (q *QuickSortMedian) medianThree(nums []int, left, mid, right int) int {
}
/* 哨兵划分（三数取中值）*/
func (q *QuickSortMedian) partition(nums []int, left, right int) int {
func (q *quickSortMedian) partition(nums []int, left, right int) int {
// 以 nums[left] 作为基准数
med := q.medianThree(nums, left, (left+right)/2, right)
// 将中位数交换至数组最左端
@ -79,7 +79,7 @@ func (q *QuickSortMedian) partition(nums []int, left, right int) int {
}
/* 快速排序 */
func (q *QuickSortMedian) quickSort(nums []int, left, right int) {
func (q *quickSortMedian) quickSort(nums []int, left, right int) {
// 子数组长度为 1 时终止递归
if left >= right {
return
@ -92,7 +92,7 @@ func (q *QuickSortMedian) quickSort(nums []int, left, right int) {
}
/* 哨兵划分 */
func (q *QuickSortTailCall) partition(nums []int, left, right int) int {
func (q *quickSortTailCall) partition(nums []int, left, right int) int {
// 以 nums[left] 作为基准数
i, j := left, right
for i < j {
@ -111,7 +111,7 @@ func (q *QuickSortTailCall) partition(nums []int, left, right int) int {
}
/* 快速排序（尾递归优化）*/
func (q *QuickSortTailCall) quickSort(nums []int, left, right int) {
func (q *quickSortTailCall) quickSort(nums []int, left, right int) {
// 子数组长度为 1 时终止
for left < right {
// 哨兵划分操作

8
codes/go/chapter_sorting/quick_sort/quick_sort_test.go → codes/go/chapter_sorting/quick_sort_test.go
View file

@ -2,7 +2,7 @@
// Created Time: 2022-12-12
// Author: msk397 (machangxinq@gmail.com)
package quick_sort
package chapter_sorting
import (
"fmt"
@ -11,7 +11,7 @@ import (
// 快速排序
func TestQuickSort(t *testing.T) {
q := QuickSort{}
q := quickSort{}
nums := []int{4, 1, 3, 1, 5, 2}
q.quickSort(nums, 0, len(nums)-1)
fmt.Println("快速排序完成后 nums = ", nums)
@ -19,7 +19,7 @@ func TestQuickSort(t *testing.T) {
// 快速排序（中位基准数优化）
func TestQuickSortMedian(t *testing.T) {
q := QuickSortMedian{}
q := quickSortMedian{}
nums := []int{4, 1, 3, 1, 5, 2}
q.quickSort(nums, 0, len(nums)-1)
fmt.Println("快速排序（中位基准数优化）完成后 nums = ", nums)
@ -27,7 +27,7 @@ func TestQuickSortMedian(t *testing.T) {
// 快速排序（尾递归优化）
func TestQuickSortTailCall(t *testing.T) {
q := QuickSortTailCall{}
q := quickSortTailCall{}
nums := []int{4, 1, 3, 1, 5, 2}
q.quickSort(nums, 0, len(nums)-1)
fmt.Println("快速排序（尾递归优化）完成后 nums = ", nums)

38
codes/go/chapter_stack_and_queue/array_queue.go
View file

@ -5,16 +5,16 @@
package chapter_stack_and_queue
/* 基于环形数组实现的队列 */
type ArrayQueue struct {
type arrayQueue struct {
data []int // 用于存储队列元素的数组
capacity int // 队列容量（即最多容量的元素个数）
front int // 头指针，指向队首
rear int // 尾指针，指向队尾 + 1
}
// NewArrayQueue 基于环形数组实现的队列
func NewArrayQueue(capacity int) *ArrayQueue {
return &ArrayQueue{
// newArrayQueue 基于环形数组实现的队列
func newArrayQueue(capacity int) *arrayQueue {
return &arrayQueue{
data: make([]int, capacity),
capacity: capacity,
front: 0,
@ -22,21 +22,21 @@ func NewArrayQueue(capacity int) *ArrayQueue {
}
}
// Size 获取队列的长度
func (q *ArrayQueue) Size() int {
// size 获取队列的长度
func (q *arrayQueue) size() int {
size := (q.capacity + q.rear - q.front) % q.capacity
return size
}
// IsEmpty 判断队列是否为空
func (q *ArrayQueue) IsEmpty() bool {
// isEmpty 判断队列是否为空
func (q *arrayQueue) isEmpty() bool {
return q.rear-q.front == 0
}
// Offer 入队
func (q *ArrayQueue) Offer(v int) {
// offer 入队
func (q *arrayQueue) offer(v int) {
// 当 rear == capacity 表示队列已满
if q.Size() == q.capacity {
if q.size() == q.capacity {
return
}
// 尾结点后添加
@ -45,9 +45,9 @@ func (q *ArrayQueue) Offer(v int) {
q.rear = (q.rear + 1) % q.capacity
}
// Poll 出队
func (q *ArrayQueue) Poll() any {
if q.IsEmpty() {
// poll 出队
func (q *arrayQueue) poll() any {
if q.isEmpty() {
return nil
}
v := q.data[q.front]
@ -56,9 +56,9 @@ func (q *ArrayQueue) Poll() any {
return v
}
// Peek 访问队首元素
func (q *ArrayQueue) Peek() any {
if q.IsEmpty() {
// peek 访问队首元素
func (q *arrayQueue) peek() any {
if q.isEmpty() {
return nil
}
v := q.data[q.front]
@ -66,6 +66,6 @@ func (q *ArrayQueue) Peek() any {
}
// 获取 Slice 用于打印
func (s *ArrayQueue) toSlice() []int {
return s.data[s.front:s.rear]
func (q *arrayQueue) toSlice() []int {
return q.data[q.front:q.rear]
}

36
codes/go/chapter_stack_and_queue/array_stack.go
View file

@ -5,47 +5,47 @@
package chapter_stack_and_queue
/* 基于数组实现的栈 */
type ArrayStack struct {
type arrayStack struct {
data []int // 数据
}
func NewArrayStack() *ArrayStack {
return &ArrayStack{
func newArrayStack() *arrayStack {
return &arrayStack{
// 设置栈的长度为 0，容量为 16
data: make([]int, 0, 16),
}
}
// Size 栈的长度
func (s *ArrayStack) Size() int {
// size 栈的长度
func (s *arrayStack) size() int {
return len(s.data)
}
// IsEmpty 栈是否为空
func (s *ArrayStack) IsEmpty() bool {
return s.Size() == 0
// isEmpty 栈是否为空
func (s *arrayStack) isEmpty() bool {
return s.size() == 0
}
// Push 入栈
func (s *ArrayStack) Push(v int) {
// push 入栈
func (s *arrayStack) push(v int) {
// 切片会自动扩容
s.data = append(s.data, v)
}
// Pop 出栈
func (s *ArrayStack) Pop() any {
// pop 出栈
func (s *arrayStack) pop() any {
// 弹出栈前，先判断是否为空
if s.IsEmpty() {
if s.isEmpty() {
return nil
}
val := s.Peek()
val := s.peek()
s.data = s.data[:len(s.data)-1]
return val
}
// Peek 获取栈顶元素
func (s *ArrayStack) Peek() any {
if s.IsEmpty() {
// peek 获取栈顶元素
func (s *arrayStack) peek() any {
if s.isEmpty() {
return nil
}
val := s.data[len(s.data)-1]
@ -53,6 +53,6 @@ func (s *ArrayStack) Peek() any {
}
// 获取 Slice 用于打印
func (s *ArrayStack) toSlice() []int {
func (s *arrayStack) toSlice() []int {
return s.data
}

30
codes/go/chapter_stack_and_queue/deque_test.go
View file

@ -51,48 +51,48 @@ func TestDeque(t *testing.T) {
func TestLinkedListDeque(t *testing.T) {
// 初始化队列
deque := NewLinkedListDeque()
deque := newLinkedListDeque()
// 元素入队
deque.OfferLast(2)
deque.OfferLast(5)
deque.OfferLast(4)
deque.OfferFirst(3)
deque.OfferFirst(1)
deque.offerLast(2)
deque.offerLast(5)
deque.offerLast(4)
deque.offerFirst(3)
deque.offerFirst(1)
fmt.Print("队列 deque = ")
PrintList(deque.toList())
// 访问队首元素
front := deque.PeekFirst()
front := deque.peekFirst()
fmt.Println("队首元素 front =", front)
rear := deque.PeekLast()
rear := deque.peekLast()
fmt.Println("队尾元素 rear =", rear)
// 元素出队
pollFirst := deque.PollFirst()
pollFirst := deque.pollFirst()
fmt.Print("队首出队元素 pollFirst = ", pollFirst, "，队首出队后 deque = ")
PrintList(deque.toList())
pollLast := deque.PollLast()
pollLast := deque.pollLast()
fmt.Print("队尾出队元素 pollLast = ", pollLast, "，队尾出队后 deque = ")
PrintList(deque.toList())
// 获取队的长度
size := deque.Size()
size := deque.size()
fmt.Println("队的长度 size =", size)
// 判断是否为空
isEmpty := deque.IsEmpty()
isEmpty := deque.isEmpty()
fmt.Println("队是否为空 =", isEmpty)
}
// BenchmarkArrayQueue 67.92 ns/op in Mac M1 Pro
func BenchmarkLinkedListDeque(b *testing.B) {
stack := NewLinkedListDeque()
stack := newLinkedListDeque()
// use b.N for looping
for i := 0; i < b.N; i++ {
stack.OfferLast(777)
stack.offerLast(777)
}
for i := 0; i < b.N; i++ {
stack.PollFirst()
stack.pollFirst()
}
}

52
codes/go/chapter_stack_and_queue/linkedlist_deque.go
View file

@ -8,31 +8,31 @@ import (
"container/list"
)
// LinkedListDeque 基于链表实现的双端队列, 使用内置包 list 来实现栈
type LinkedListDeque struct {
// linkedListDeque 基于链表实现的双端队列, 使用内置包 list 来实现栈
type linkedListDeque struct {
data *list.List
}
// NewLinkedListDeque 初始化双端队列
func NewLinkedListDeque() *LinkedListDeque {
return &LinkedListDeque{
// newLinkedListDeque 初始化双端队列
func newLinkedListDeque() *linkedListDeque {
return &linkedListDeque{
data: list.New(),
}
}
// OfferFirst 队首元素入队
func (s *LinkedListDeque) OfferFirst(value any) {
// offerFirst 队首元素入队
func (s *linkedListDeque) offerFirst(value any) {
s.data.PushFront(value)
}
// OfferLast 队尾元素入队
func (s *LinkedListDeque) OfferLast(value any) {
// offerLast 队尾元素入队
func (s *linkedListDeque) offerLast(value any) {
s.data.PushBack(value)
}
// PollFirst 队首元素出队
func (s *LinkedListDeque) PollFirst() any {
if s.IsEmpty() {
// pollFirst 队首元素出队
func (s *linkedListDeque) pollFirst() any {
if s.isEmpty() {
return nil
}
e := s.data.Front()
@ -40,9 +40,9 @@ func (s *LinkedListDeque) PollFirst() any {
return e.Value
}
// PollLast 队尾元素出队
func (s *LinkedListDeque) PollLast() any {
if s.IsEmpty() {
// pollLast 队尾元素出队
func (s *linkedListDeque) pollLast() any {
if s.isEmpty() {
return nil
}
e := s.data.Back()
@ -50,35 +50,35 @@ func (s *LinkedListDeque) PollLast() any {
return e.Value
}
// PeekFirst 访问队首元素
func (s *LinkedListDeque) PeekFirst() any {
if s.IsEmpty() {
// peekFirst 访问队首元素
func (s *linkedListDeque) peekFirst() any {
if s.isEmpty() {
return nil
}
e := s.data.Front()
return e.Value
}
// PeekLast 访问队尾元素
func (s *LinkedListDeque) PeekLast() any {
if s.IsEmpty() {
// peekLast 访问队尾元素
func (s *linkedListDeque) peekLast() any {
if s.isEmpty() {
return nil
}
e := s.data.Back()
return e.Value
}
// Size 获取队列的长度
func (s *LinkedListDeque) Size() int {
// size 获取队列的长度
func (s *linkedListDeque) size() int {
return s.data.Len()
}
// IsEmpty 判断队列是否为空
func (s *LinkedListDeque) IsEmpty() bool {
// isEmpty 判断队列是否为空
func (s *linkedListDeque) isEmpty() bool {
return s.data.Len() == 0
}
// 获取 List 用于打印
func (s *LinkedListDeque) toList() *list.List {
func (s *linkedListDeque) toList() *list.List {
return s.data
}

34
codes/go/chapter_stack_and_queue/linkedlist_queue.go
View file

@ -9,26 +9,26 @@ import (
)
/* 基于链表实现的队列 */
type LinkedListQueue struct {
type linkedListQueue struct {
// 使用内置包 list 来实现队列
data *list.List
}
// NewLinkedListQueue 初始化链表
func NewLinkedListQueue() *LinkedListQueue {
return &LinkedListQueue{
// newLinkedListQueue 初始化链表
func newLinkedListQueue() *linkedListQueue {
return &linkedListQueue{
data: list.New(),
}
}
// Offer 入队
func (s *LinkedListQueue) Offer(value any) {
// offer 入队
func (s *linkedListQueue) offer(value any) {
s.data.PushBack(value)
}
// Poll 出队
func (s *LinkedListQueue) Poll() any {
if s.IsEmpty() {
// poll 出队
func (s *linkedListQueue) poll() any {
if s.isEmpty() {
return nil
}
e := s.data.Front()
@ -36,26 +36,26 @@ func (s *LinkedListQueue) Poll() any {
return e.Value
}
// Peek 访问队首元素
func (s *LinkedListQueue) Peek() any {
if s.IsEmpty() {
// peek 访问队首元素
func (s *linkedListQueue) peek() any {
if s.isEmpty() {
return nil
}
e := s.data.Front()
return e.Value
}
// Size 获取队列的长度
func (s *LinkedListQueue) Size() int {
// size 获取队列的长度
func (s *linkedListQueue) size() int {
return s.data.Len()
}
// IsEmpty 判断队列是否为空
func (s *LinkedListQueue) IsEmpty() bool {
// isEmpty 判断队列是否为空
func (s *linkedListQueue) isEmpty() bool {
return s.data.Len() == 0
}
// 获取 List 用于打印
func (s *LinkedListQueue) toList() *list.List {
func (s *linkedListQueue) toList() *list.List {
return s.data
}

34
codes/go/chapter_stack_and_queue/linkedlist_stack.go
View file

@ -9,26 +9,26 @@ import (
)
/* 基于链表实现的栈 */
type LinkedListStack struct {
type linkedListStack struct {
// 使用内置包 list 来实现栈
data *list.List
}
// NewLinkedListStack 初始化链表
func NewLinkedListStack() *LinkedListStack {
return &LinkedListStack{
// newLinkedListStack 初始化链表
func newLinkedListStack() *linkedListStack {
return &linkedListStack{
data: list.New(),
}
}
// Push 入栈
func (s *LinkedListStack) Push(value int) {
// push 入栈
func (s *linkedListStack) push(value int) {
s.data.PushBack(value)
}
// Pop 出栈
func (s *LinkedListStack) Pop() any {
if s.IsEmpty() {
// pop 出栈
func (s *linkedListStack) pop() any {
if s.isEmpty() {
return nil
}
e := s.data.Back()
@ -36,26 +36,26 @@ func (s *LinkedListStack) Pop() any {
return e.Value
}
// Peek 访问栈顶元素
func (s *LinkedListStack) Peek() any {
if s.IsEmpty() {
// peek 访问栈顶元素
func (s *linkedListStack) peek() any {
if s.isEmpty() {
return nil
}
e := s.data.Back()
return e.Value
}
// Size 获取栈的长度
func (s *LinkedListStack) Size() int {
// size 获取栈的长度
func (s *linkedListStack) size() int {
return s.data.Len()
}
// IsEmpty 判断栈是否为空
func (s *LinkedListStack) IsEmpty() bool {
// isEmpty 判断栈是否为空
func (s *linkedListStack) isEmpty() bool {
return s.data.Len() == 0
}
// 获取 List 用于打印
func (s *LinkedListStack) toList() *list.List {
func (s *linkedListStack) toList() *list.List {
return s.data
}

52
codes/go/chapter_stack_and_queue/queue_test.go
View file

@ -48,87 +48,87 @@ func TestQueue(t *testing.T) {
func TestArrayQueue(t *testing.T) {
// 初始化队列，使用队列的通用接口
capacity := 10
queue := NewArrayQueue(capacity)
queue := newArrayQueue(capacity)
// 元素入队
queue.Offer(1)
queue.Offer(3)
queue.Offer(2)
queue.Offer(5)
queue.Offer(4)
queue.offer(1)
queue.offer(3)
queue.offer(2)
queue.offer(5)
queue.offer(4)
fmt.Print("队列 queue = ")
PrintSlice(queue.toSlice())
// 访问队首元素
peek := queue.Peek()
peek := queue.peek()
fmt.Println("队首元素 peek =", peek)
// 元素出队
poll := queue.Poll()
poll := queue.poll()
fmt.Print("出队元素 poll = ", poll, ", 出队后 queue = ")
PrintSlice(queue.toSlice())
// 获取队的长度
size := queue.Size()
size := queue.size()
fmt.Println("队的长度 size =", size)
// 判断是否为空
isEmpty := queue.IsEmpty()
isEmpty := queue.isEmpty()
fmt.Println("队是否为空 =", isEmpty)
}
func TestLinkedListQueue(t *testing.T) {
// 初始化队
queue := NewLinkedListQueue()
queue := newLinkedListQueue()
// 元素入队
queue.Offer(1)
queue.Offer(3)
queue.Offer(2)
queue.Offer(5)
queue.Offer(4)
queue.offer(1)
queue.offer(3)
queue.offer(2)
queue.offer(5)
queue.offer(4)
fmt.Print("队列 queue = ")
PrintList(queue.toList())
// 访问队首元素
peek := queue.Peek()
peek := queue.peek()
fmt.Println("队首元素 peek =", peek)
// 元素出队
poll := queue.Poll()
poll := queue.poll()
fmt.Print("出队元素 poll = ", poll, ", 出队后 queue = ")
PrintList(queue.toList())
// 获取队的长度
size := queue.Size()
size := queue.size()
fmt.Println("队的长度 size =", size)
// 判断是否为空
isEmpty := queue.IsEmpty()
isEmpty := queue.isEmpty()
fmt.Println("队是否为空 =", isEmpty)
}
// BenchmarkArrayQueue 8 ns/op in Mac M1 Pro
func BenchmarkArrayQueue(b *testing.B) {
capacity := 1000
stack := NewArrayQueue(capacity)
stack := newArrayQueue(capacity)
// use b.N for looping
for i := 0; i < b.N; i++ {
stack.Offer(777)
stack.offer(777)
}
for i := 0; i < b.N; i++ {
stack.Poll()
stack.poll()
}
}
// BenchmarkLinkedQueue 62.66 ns/op in Mac M1 Pro
func BenchmarkLinkedQueue(b *testing.B) {
stack := NewLinkedListQueue()
stack := newLinkedListQueue()
// use b.N for looping
for i := 0; i < b.N; i++ {
stack.Offer(777)
stack.offer(777)
}
for i := 0; i < b.N; i++ {
stack.Poll()
stack.poll()
}
}

52
codes/go/chapter_stack_and_queue/stack_test.go
View file

@ -46,85 +46,85 @@ func TestStack(t *testing.T) {
func TestArrayStack(t *testing.T) {
// 初始化栈, 使用接口承接
stack := NewArrayStack()
stack := newArrayStack()
// 元素入栈
stack.Push(1)
stack.Push(3)
stack.Push(2)
stack.Push(5)
stack.Push(4)
stack.push(1)
stack.push(3)
stack.push(2)
stack.push(5)
stack.push(4)
fmt.Print("栈 stack = ")
PrintSlice(stack.toSlice())
// 访问栈顶元素
peek := stack.Peek()
peek := stack.peek()
fmt.Println("栈顶元素 peek =", peek)
// 元素出栈
pop := stack.Pop()
pop := stack.pop()
fmt.Print("出栈元素 pop = ", pop, ", 出栈后 stack = ")
PrintSlice(stack.toSlice())
// 获取栈的长度
size := stack.Size()
size := stack.size()
fmt.Println("栈的长度 size =", size)
// 判断是否为空
isEmpty := stack.IsEmpty()
isEmpty := stack.isEmpty()
fmt.Println("栈是否为空 =", isEmpty)
}
func TestLinkedListStack(t *testing.T) {
// 初始化栈
stack := NewLinkedListStack()
stack := newLinkedListStack()
// 元素入栈
stack.Push(1)
stack.Push(3)
stack.Push(2)
stack.Push(5)
stack.Push(4)
stack.push(1)
stack.push(3)
stack.push(2)
stack.push(5)
stack.push(4)
fmt.Print("栈 stack = ")
PrintList(stack.toList())
// 访问栈顶元素
peek := stack.Peek()
peek := stack.peek()
fmt.Println("栈顶元素 peek =", peek)
// 元素出栈
pop := stack.Pop()
pop := stack.pop()
fmt.Print("出栈元素 pop = ", pop, ", 出栈后 stack = ")
PrintList(stack.toList())
// 获取栈的长度
size := stack.Size()
size := stack.size()
fmt.Println("栈的长度 size =", size)
// 判断是否为空
isEmpty := stack.IsEmpty()
isEmpty := stack.isEmpty()
fmt.Println("栈是否为空 =", isEmpty)
}
// BenchmarkArrayStack 8 ns/op in Mac M1 Pro
func BenchmarkArrayStack(b *testing.B) {
stack := NewArrayStack()
stack := newArrayStack()
// use b.N for looping
for i := 0; i < b.N; i++ {
stack.Push(777)
stack.push(777)
}
for i := 0; i < b.N; i++ {
stack.Pop()
stack.pop()
}
}
// BenchmarkLinkedListStack 65.02 ns/op in Mac M1 Pro
func BenchmarkLinkedListStack(b *testing.B) {
stack := NewLinkedListStack()
stack := newLinkedListStack()
// use b.N for looping
for i := 0; i < b.N; i++ {
stack.Push(777)
stack.push(777)
}
for i := 0; i < b.N; i++ {
stack.Pop()
stack.pop()
}
}

211
codes/go/chapter_tree/avl_tree.go Normal file
View file

@ -0,0 +1,211 @@
// File: avl_tree.go
// Created Time: 2023-01-08
// Author: Reanon (793584285@qq.com)
package chapter_tree
import . "github.com/krahets/hello-algo/pkg"
/* AVL Tree*/
type avlTree struct {
// 根节点
root *TreeNode
}
func newAVLTree() *avlTree {
return &avlTree{root: nil}
}
/* 获取结点高度 */
func height(node *TreeNode) int {
// 空结点高度为 -1 ，叶结点高度为 0
if node != nil {
return node.Height
}
return -1
}
/* 更新结点高度 */
func updateHeight(node *TreeNode) {
lh := height(node.Left)
rh := height(node.Right)
// 结点高度等于最高子树高度 + 1
if lh > rh {
node.Height = lh + 1
} else {
node.Height = rh + 1
}
}
/* 获取平衡因子 */
func balanceFactor(node *TreeNode) int {
// 空结点平衡因子为 0
if node == nil {
return 0
}
// 结点平衡因子 = 左子树高度 - 右子树高度
return height(node.Left) - height(node.Right)
}
/* 右旋操作 */
func rightRotate(node *TreeNode) *TreeNode {
child := node.Left
grandChild := child.Right
// 以 child 为原点，将 node 向右旋转
child.Right = node
node.Left = grandChild
// 更新结点高度
updateHeight(node)
updateHeight(child)
// 返回旋转后子树的根节点
return child
}
/* 左旋操作 */
func leftRotate(node *TreeNode) *TreeNode {
child := node.Right
grandChild := child.Left
// 以 child 为原点，将 node 向左旋转
child.Left = node
node.Right = grandChild
// 更新结点高度
updateHeight(node)
updateHeight(child)
// 返回旋转后子树的根节点
return child
}
/* 执行旋转操作，使该子树重新恢复平衡 */
func rotate(node *TreeNode) *TreeNode {
// 获取结点 node 的平衡因子
// Go 推荐短变量，这里 bf 指代 balanceFactor
bf := balanceFactor(node)
// 左偏树
if bf > 1 {
if balanceFactor(node.Left) >= 0 {
// 右旋
return rightRotate(node)
} else {
// 先左旋后右旋
node.Left = leftRotate(node.Left)
return rightRotate(node)
}
}
// 右偏树
if bf < -1 {
if balanceFactor(node.Right) <= 0 {
// 左旋
return leftRotate(node)
} else {
// 先右旋后左旋
node.Right = rightRotate(node.Right)
return leftRotate(node)
}
}
// 平衡树，无需旋转，直接返回
return node
}
/* 插入结点 */
func (t *avlTree) insert(val int) *TreeNode {
t.root = insertHelper(t.root, val)
return t.root
}
/* 递归插入结点（辅助函数） */
func insertHelper(node *TreeNode, val int) *TreeNode {
if node == nil {
return NewTreeNode(val)
}
/* 1. 查找插入位置，并插入结点 */
if val < node.Val {
node.Left = insertHelper(node.Left, val)
} else if val > node.Val {
node.Right = insertHelper(node.Right, val)
} else {
// 重复结点不插入，直接返回
return node
}
// 更新结点高度
updateHeight(node)
/* 2. 执行旋转操作，使该子树重新恢复平衡 */
node = rotate(node)
// 返回子树的根节点
return node
}
/* 删除结点 */
func (t *avlTree) remove(val int) *TreeNode {
root := removeHelper(t.root, val)
return root
}
/* 递归删除结点（辅助函数） */
func removeHelper(node *TreeNode, val int) *TreeNode {
if node == nil {
return nil
}
/* 1. 查找结点，并删除之 */
if val < node.Val {
node.Left = removeHelper(node.Left, val)
} else if val > node.Val {
node.Right = removeHelper(node.Right, val)
} else {
if node.Left == nil || node.Right == nil {
child := node.Left
if node.Right != nil {
child = node.Right
}
// 子结点数量 = 0 ，直接删除 node 并返回
if child == nil {
return nil
} else {
// 子结点数量 = 1 ，直接删除 node
node = child
}
} else {
// 子结点数量 = 2 ，则将中序遍历的下个结点删除，并用该结点替换当前结点
temp := getInOrderNext(node.Right)
node.Right = removeHelper(node.Right, temp.Val)
node.Val = temp.Val
}
}
// 更新结点高度
updateHeight(node)
/* 2. 执行旋转操作，使该子树重新恢复平衡 */
node = rotate(node)
// 返回子树的根节点
return node
}
/* 获取中序遍历中的下一个结点（仅适用于 root 有左子结点的情况） */
func getInOrderNext(node *TreeNode) *TreeNode {
if node == nil {
return node
}
// 循环访问左子结点，直到叶结点时为最小结点，跳出
for node.Left != nil {
node = node.Left
}
return node
}
/* 查找结点 */
func (t *avlTree) search(val int) *TreeNode {
cur := t.root
// 循环查找，越过叶结点后跳出
for cur != nil {
// 目标结点在 root 的右子树中
if cur.Val < val {
cur = cur.Right
} else if cur.Val > val {
// 目标结点在 root 的左子树中
cur = cur.Left
} else {
// 找到目标结点，跳出循环
break
}
}
// 返回目标结点
return cur
}

54
codes/go/chapter_tree/avl_tree_test.go Normal file
View file

@ -0,0 +1,54 @@
// File: avl_tree_test.go
// Created Time: 2023-01-08
// Author: Reanon (793584285@qq.com)
package chapter_tree
import (
"fmt"
"testing"
. "github.com/krahets/hello-algo/pkg"
)
func TestAVLTree(t *testing.T) {
/* 初始化空 AVL 树 */
tree := newAVLTree()
/* 插入结点 */
// 请关注插入结点后，AVL 树是如何保持平衡的
testInsert(tree, 1)
testInsert(tree, 2)
testInsert(tree, 3)
testInsert(tree, 4)
testInsert(tree, 5)
testInsert(tree, 8)
testInsert(tree, 7)
testInsert(tree, 9)
testInsert(tree, 10)
testInsert(tree, 6)
/* 插入重复结点 */
testInsert(tree, 7)
/* 删除结点 */
// 请关注删除结点后，AVL 树是如何保持平衡的
testRemove(tree, 8) // 删除度为 0 的结点
testRemove(tree, 5) // 删除度为 1 的结点
testRemove(tree, 4) // 删除度为 2 的结点
/* 查询结点 */
node := tree.search(7)
fmt.Printf("\n查找到的结点对象为 %#v ，结点值 = %d \n", node, node.Val)
}
func testInsert(tree *avlTree, val int) {
tree.insert(val)
fmt.Printf("\n插入结点 %d 后，AVL 树为 \n", val)
PrintTree(tree.root)
}
func testRemove(tree *avlTree, val int) {
tree.remove(val)
fmt.Printf("\n删除结点 %d 后，AVL 树为 \n", val)
PrintTree(tree.root)
}

41
codes/go/chapter_tree/binary_search_tree.go
View file

@ -10,26 +10,26 @@ import (
. "github.com/krahets/hello-algo/pkg"
)
type BinarySearchTree struct {
type binarySearchTree struct {
root *TreeNode
}
func NewBinarySearchTree(nums []int) *BinarySearchTree {
func newBinarySearchTree(nums []int) *binarySearchTree {
// sorting array
sort.Ints(nums)
root := buildBinarySearchTree(nums, 0, len(nums)-1)
return &BinarySearchTree{
return &binarySearchTree{
root: root,
}
}
// GetRoot Get the root node of binary search tree
func (bst *BinarySearchTree) GetRoot() *TreeNode {
/* 获取根结点 */
func (bst *binarySearchTree) getRoot() *TreeNode {
return bst.root
}
// GetMin Get node with the min value
func (bst *BinarySearchTree) GetMin(node *TreeNode) *TreeNode {
/* 获取中序遍历的下一个结点 */
func (bst *binarySearchTree) getInOrderNext(node *TreeNode) *TreeNode {
if node == nil {
return node
}
@ -40,21 +40,8 @@ func (bst *BinarySearchTree) GetMin(node *TreeNode) *TreeNode {
return node
}
// GetInorderNext Get node inorder next
func (bst *BinarySearchTree) GetInorderNext(node *TreeNode) *TreeNode {
if node == nil || node.Right == nil {
return node
}
node = node.Right
// 循环访问左子结点，直到叶结点时为最小结点，跳出
for node.Left != nil {
node = node.Left
}
return node
}
/* 查找结点 */
func (bst *BinarySearchTree) Search(num int) *TreeNode {
func (bst *binarySearchTree) search(num int) *TreeNode {
node := bst.root
// 循环查找，越过叶结点后跳出
for node != nil {
@ -74,7 +61,7 @@ func (bst *BinarySearchTree) Search(num int) *TreeNode {
}
/* 插入结点 */
func (bst *BinarySearchTree) Insert(num int) *TreeNode {
func (bst *binarySearchTree) insert(num int) *TreeNode {
cur := bst.root
// 若树为空，直接提前返回
if cur == nil {
@ -105,7 +92,7 @@ func (bst *BinarySearchTree) Insert(num int) *TreeNode {
}
/* 删除结点 */
func (bst *BinarySearchTree) Remove(num int) *TreeNode {
func (bst *binarySearchTree) remove(num int) *TreeNode {
cur := bst.root
// 若树为空，直接提前返回
if cur == nil {
@ -149,10 +136,10 @@ func (bst *BinarySearchTree) Remove(num int) *TreeNode {
// 子结点数为 2
} else {
// 获取中序遍历中待删除结点 cur 的下一个结点
next := bst.GetInorderNext(cur)
next := bst.getInOrderNext(cur)
temp := next.Val
// 递归删除结点 next
bst.Remove(next.Val)
bst.remove(next.Val)
// 将 next 的值复制给 cur
cur.Val = temp
}
@ -173,7 +160,7 @@ func buildBinarySearchTree(nums []int, left, right int) *TreeNode {
return root
}
// Print binary search tree
func (bst *BinarySearchTree) Print() {
// print binary search tree
func (bst *binarySearchTree) print() {
PrintTree(bst.root)
}

39
codes/go/chapter_tree/binary_search_tree_test.go
View file

@ -11,34 +11,31 @@ import (
func TestBinarySearchTree(t *testing.T) {
nums := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
bst := NewBinarySearchTree(nums)
fmt.Println("初始化的二叉树为:")
bst.Print()
bst := newBinarySearchTree(nums)
fmt.Println("\n初始化的二叉树为:")
bst.print()
// 获取根结点
node := bst.GetRoot()
fmt.Println("二叉树的根结点为:", node.Val)
// 获取最小的结点
node = bst.GetMin(bst.GetRoot())
fmt.Println("二叉树的最小结点为:", node.Val)
node := bst.getRoot()
fmt.Println("\n二叉树的根结点为:", node.Val)
// 查找结点
node = bst.Search(5)
node = bst.search(7)
fmt.Println("查找到的结点对象为", node, "，结点值 =", node.Val)
// 插入结点
node = bst.Insert(16)
fmt.Println("插入结点后 16 的二叉树为:")
bst.Print()
node = bst.insert(16)
fmt.Println("\n插入结点后 16 的二叉树为:")
bst.print()
// 删除结点
bst.Remove(1)
fmt.Println("删除结点 1 后的二叉树为:")
bst.Print()
bst.Remove(2)
fmt.Println("删除结点 2 后的二叉树为:")
bst.Print()
bst.Remove(4)
fmt.Println("删除结点 4 后的二叉树为:")
bst.Print()
bst.remove(1)
fmt.Println("\n删除结点 1 后的二叉树为:")
bst.print()
bst.remove(2)
fmt.Println("\n删除结点 2 后的二叉树为:")
bst.print()
bst.remove(4)
fmt.Println("\n删除结点 4 后的二叉树为:")
bst.print()
}

6
codes/go/chapter_tree/binary_tree_bfs_test.go
View file

@ -14,11 +14,11 @@ import (
func TestLevelOrder(t *testing.T) {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
root := ArrayToTree([]int{1, 2, 3, 4, 5, 6, 7})
fmt.Println("初始化二叉树: ")
root := ArrToTree([]any{1, 2, 3, 4, 5, 6, 7})
fmt.Println("\n初始化二叉树: ")
PrintTree(root)
// 层序遍历
nums := levelOrder(root)
fmt.Println("层序遍历的结点打印序列 =", nums)
fmt.Println("\n层序遍历的结点打印序列 =", nums)
}

10
codes/go/chapter_tree/binary_tree_dfs_test.go
View file

@ -14,22 +14,22 @@ import (
func TestPreInPostOrderTraversal(t *testing.T) {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
root := ArrayToTree([]int{1, 2, 3, 4, 5, 6, 7})
fmt.Println("初始化二叉树: ")
root := ArrToTree([]any{1, 2, 3, 4, 5, 6, 7})
fmt.Println("\n初始化二叉树: ")
PrintTree(root)
// 前序遍历
nums = nil
preOrder(root)
fmt.Println("前序遍历的结点打印序列 =", nums)
fmt.Println("\n前序遍历的结点打印序列 =", nums)
// 中序遍历
nums = nil
inOrder(root)
fmt.Println("中序遍历的结点打印序列 =", nums)
fmt.Println("\n中序遍历的结点打印序列 =", nums)
// 后序遍历
nums = nil
postOrder(root)
fmt.Println("后序遍历的结点打印序列 =", nums)
fmt.Println("\n后序遍历的结点打印序列 =", nums)
}

4
codes/go/pkg/print_utils.go
View file

@ -76,7 +76,7 @@ func printTreeHelper(root *TreeNode, prev *trunk, isLeft bool) {
printTreeHelper(root.Left, trunk, false)
}
// trunk Help to Print tree structure
// trunk Help to print tree structure
type trunk struct {
prev *trunk
str string
@ -103,4 +103,4 @@ func PrintMap[K comparable, V any](m map[K]V) {
for key, value := range m {
fmt.Println(key, "->", value)
}
}
}

39
codes/go/pkg/tree_node.go
View file

@ -9,41 +9,48 @@ import (
)
type TreeNode struct {
Val int
Left *TreeNode
Right *TreeNode
Val int // 结点值
Height int // 结点高度
Left *TreeNode // 左子结点引用
Right *TreeNode // 右子结点引用
}
func NewTreeNode(v int) *TreeNode {
return &TreeNode{
Left: nil,
Right: nil,
Val: v,
Val: v,
Height: 0,
Left: nil,
Right: nil,
}
}
// ArrayToTree Generate a binary tree with an array
func ArrayToTree(arr []int) *TreeNode {
// ArrToTree Generate a binary tree given an array
func ArrToTree(arr []any) *TreeNode {
if len(arr) <= 0 {
return nil
}
root := NewTreeNode(arr[0])
// TreeNode only accept integer value for now.
root := NewTreeNode(arr[0].(int))
// Let container.list as queue
queue := list.New()
queue.PushBack(root)
i := 1
i := 0
for queue.Len() > 0 {
// poll
node := queue.Remove(queue.Front()).(*TreeNode)
i++
if i < len(arr) {
node.Left = NewTreeNode(arr[i])
queue.PushBack(node.Left)
i++
if arr[i] != nil {
node.Left = NewTreeNode(arr[i].(int))
queue.PushBack(node.Left)
}
}
i++
if i < len(arr) {
node.Right = NewTreeNode(arr[i])
queue.PushBack(node.Right)
i++
if arr[i] != nil {
node.Right = NewTreeNode(arr[i].(int))
queue.PushBack(node.Right)
}
}
}
return root

4
codes/go/pkg/tree_node_test.go
View file

@ -10,8 +10,8 @@ import (
)
func TestTreeNode(t *testing.T) {
arr := []int{2, 3, 5, 6, 7}
node := ArrayToTree(arr)
arr := []any{1, 2, 3, nil, 5, 6, nil}
node := ArrToTree(arr)
// print tree
PrintTree(node)

2
codes/java/chapter_array_and_linkedlist/array.java
View file

@ -1,4 +1,4 @@
/*
/**
* File: array.java
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)

4
codes/java/chapter_array_and_linkedlist/linked_list.java
View file

@ -1,4 +1,4 @@
/*
/**
* File: linked_list.java
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
@ -29,9 +29,9 @@ public class linked_list {
/* 访问链表中索引为 index 的结点 */
static ListNode access(ListNode head, int index) {
for (int i = 0; i < index; i++) {
head = head.next;
if (head == null)
return null;
head = head.next;
}
return head;
}

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