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refactor: Improve the hash_map_chaining.c implementation. (#858)
* Improve the hash_map_chaining.c implementation. * Update hash_map_chaining.c
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2 changed files with 129 additions and 154 deletions
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@ -1,67 +1,62 @@
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/**
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* File: hash_map_chaining.c
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* Created Time: 2023-08-29
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* Author: SenMing (1206575349@qq.com)
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* Created Time: 2023-10-13
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* Author: SenMing (1206575349@qq.com), Krahets (krahets@163.com)
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*/
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#include "../utils/common.h"
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/* 键值对 int->string */
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struct node {
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int key;
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char *val;
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struct node *next; // 下一个元素
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};
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typedef struct node Node;
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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/* 键值对 */
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struct pair {
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Node *node; // 键值对节点
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int key;
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char val[100]; // 假设 val 最大长度为 100
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};
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typedef struct pair Pair;
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/* 基于数组简易实现的链式地址哈希表 */
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/* 链表节点 */
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struct node {
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Pair *pair;
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struct Node *next;
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};
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typedef struct node Node;
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/* 链式地址哈希表 */
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struct hashMapChaining {
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int size; // 键值对数量
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int capacity; // 哈希表容量
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double loadThres; // 触发扩容的负载因子阈值
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int extendRatio; // 扩容倍数
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Pair *buckets; // 桶数组
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Node **buckets; // 桶数组
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};
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typedef struct hashMapChaining hashMapChaining;
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// 函数声明
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void extend(hashMapChaining *hashMap);
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/* 初始化桶数组 */
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hashMapChaining *newHashMapChaining() {
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// 为哈希表分配空间
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int tableSize = 4;
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/* 构造方法 */
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hashMapChaining *initHashMapChaining() {
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hashMapChaining *hashMap = (hashMapChaining *)malloc(sizeof(hashMapChaining));
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// 初始化数组
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hashMap->buckets = (Pair *)malloc(sizeof(Pair) * tableSize);
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memset(hashMap->buckets, 0, sizeof(Pair) * tableSize);
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hashMap->capacity = tableSize;
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hashMap->size = 0;
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hashMap->extendRatio = 2;
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hashMap->capacity = 4;
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hashMap->loadThres = 2.0 / 3.0;
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hashMap->extendRatio = 2;
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hashMap->buckets = (Node **)malloc(hashMap->capacity * sizeof(Node *));
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for (int i = 0; i < hashMap->capacity; i++) {
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hashMap->buckets[i] = NULL;
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}
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return hashMap;
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}
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/* 销毁哈希表 */
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void delHashMapChaining(hashMapChaining *hashMap) {
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/* 析构方法 */
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void freeHashMapChaining(hashMapChaining *hashMap) {
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for (int i = 0; i < hashMap->capacity; i++) {
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Pair *pair = &hashMap->buckets[i];
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Node *node = pair->node;
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while (node != NULL) {
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Node *temp = node;
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node = node->next;
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free(temp->val);
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Node *cur = hashMap->buckets[i];
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while (cur) {
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Node *temp = cur;
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cur = cur->next;
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free(temp->pair);
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free(temp);
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}
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}
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@ -70,7 +65,7 @@ void delHashMapChaining(hashMapChaining *hashMap) {
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}
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/* 哈希函数 */
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int hashFunc(hashMapChaining *hashMap, const int key) {
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int hashFunc(hashMapChaining *hashMap, int key) {
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return key % hashMap->capacity;
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}
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@ -80,164 +75,142 @@ double loadFactor(hashMapChaining *hashMap) {
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}
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/* 查询操作 */
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char *get(hashMapChaining *hashMap, const int key) {
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char *get(hashMapChaining *hashMap, int key) {
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int index = hashFunc(hashMap, key);
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Pair *pair = &hashMap->buckets[index];
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Node *node = pair->node;
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while (node != NULL) {
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if (node->key == key) {
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return node->val;
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// 遍历桶,若找到 key 则返回对应 val
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Node *cur = hashMap->buckets[index];
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while (cur) {
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if (cur->pair->key == key) {
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return cur->pair->val;
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}
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node = node->next;
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cur = cur->next;
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}
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return NULL;
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return ""; // 若未找到 key 则返回空字符串
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}
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/* 添加操作 */
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void put(hashMapChaining *hashMap, const int key, char *val) {
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if (loadFactor(hashMap) > hashMap->loadThres) {
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extend(hashMap);
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}
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int index = hashFunc(hashMap, key);
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// 先为新节点分配空间再赋值
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Node *newNode = (Node *)malloc(sizeof(Node));
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memset(newNode, 0, sizeof(Node));
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newNode->key = key;
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newNode->val = (char *)malloc(strlen(val) + 1);
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strcpy(newNode->val, val);
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newNode->val[strlen(val)] = '\0';
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Pair *pair = &hashMap->buckets[index];
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Node *node = pair->node;
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if (node == NULL) {
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hashMap->buckets[index].node = newNode;
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hashMap->size++;
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return;
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}
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while (node != NULL) {
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if (node->key == key) {
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// 释放先前分配的内存
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free(node->val);
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// 更新节点的值
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node->val = (char *)malloc(strlen(val) + 1);
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strcpy(node->val, val);
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node->val[strlen(val)] = '\0';
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return;
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}
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if (node->next == NULL) {
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break;
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}
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node = node->next;
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}
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node->next = newNode;
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hashMap->size++;
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}
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/* 删除操作 */
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void removeItem(hashMapChaining *hashMap, int key) {
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int index = hashFunc(hashMap, key);
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Pair *pair = &hashMap->buckets[index];
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Node *node = pair->node;
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// 保存后继的节点
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Node *prev = NULL;
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while (node != NULL) {
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if (node->key == key) {
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// 如果要删除的节点是桶的第一个节点
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if (prev == NULL) {
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pair->node = node->next;
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} else {
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prev->next = node->next;
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}
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// 释放内存
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free(node->val);
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free(node);
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hashMap->size--;
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return;
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}
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prev = node;
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node = node->next;
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}
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return;
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}
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void put(hashMapChaining *hashMap, int key, const char *val);
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/* 扩容哈希表 */
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void extend(hashMapChaining *hashMap) {
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// 暂存原哈希表
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Pair *oldBuckets = hashMap->buckets;
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int oldCapacity = hashMap->capacity;
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// 创建新的哈希表,重新分配一段空间
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Node **oldBuckets = hashMap->buckets;
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// 初始化扩容后的新哈希表
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hashMap->capacity *= hashMap->extendRatio;
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hashMap->buckets = (Pair *)malloc(sizeof(Pair) * hashMap->capacity);
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memset(hashMap->buckets, 0, sizeof(Pair) * hashMap->capacity);
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hashMap->buckets = (Node **)malloc(hashMap->capacity * sizeof(Node *));
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for (int i = 0; i < hashMap->capacity; i++) {
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hashMap->buckets[i] = NULL;
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}
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hashMap->size = 0;
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// 将原哈希表中的键值对重新哈希到新的哈希表中
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// 将键值对从原哈希表搬运至新哈希表
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for (int i = 0; i < oldCapacity; i++) {
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Node *node = oldBuckets[i].node;
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while (node != NULL) {
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put(hashMap, node->key, node->val);
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node = node->next;
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}
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}
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// 释放原哈希表的内存
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for (int i = 0; i < oldCapacity; i++) {
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Node *node = oldBuckets[i].node;
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while (node != NULL) {
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Node *temp = node;
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node = node->next;
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free(temp->val);
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Node *cur = oldBuckets[i];
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while (cur) {
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put(hashMap, cur->pair->key, cur->pair->val);
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Node *temp = cur;
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cur = cur->next;
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// 释放内存
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free(temp->pair);
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free(temp);
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}
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}
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free(oldBuckets);
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}
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/* 添加操作 */
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void put(hashMapChaining *hashMap, int key, const char *val) {
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// 当负载因子超过阈值时,执行扩容
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if (loadFactor(hashMap) > hashMap->loadThres) {
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extend(hashMap);
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}
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int index = hashFunc(hashMap, key);
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// 遍历桶,若遇到指定 key ,则更新对应 val 并返回
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Node *cur = hashMap->buckets[index];
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while (cur) {
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if (cur->pair->key == key) {
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strcpy(cur->pair->val, val); // 若遇到指定 key ,则更新对应 val 并返回
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return;
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}
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cur = cur->next;
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}
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// 若无该 key ,则将键值对添加至尾部
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Pair *newPair = (Pair *)malloc(sizeof(Pair));
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newPair->key = key;
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strcpy(newPair->val, val);
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Node *newNode = (Node *)malloc(sizeof(Node));
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newNode->pair = newPair;
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newNode->next = hashMap->buckets[index];
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hashMap->buckets[index] = newNode;
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hashMap->size++;
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}
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/* 删除操作 */
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void removeKey(hashMapChaining *hashMap, int key) {
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int index = hashFunc(hashMap, key);
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Node *cur = hashMap->buckets[index];
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Node *pre = NULL;
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while (cur) {
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if (cur->pair->key == key) {
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// 从中删除键值对
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if (pre) {
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pre->next = cur->next;
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} else {
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hashMap->buckets[index] = cur->next;
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}
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// 释放内存
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free(cur->pair);
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free(cur);
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hashMap->size--;
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return;
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}
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pre = cur;
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cur = cur->next;
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}
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}
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/* 打印哈希表 */
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void print(hashMapChaining *hashMap) {
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for (int i = 0; i < hashMap->capacity; i++) {
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Node *cur = hashMap->buckets[i];
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printf("[");
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Pair *pair = &hashMap->buckets[i];
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Node *node = pair->node;
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while (node != NULL) {
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if (node->val != NULL) {
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printf("%d->%s, ", node->key, node->val);
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}
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node = node->next;
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while (cur) {
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printf("%d -> %s, ", cur->pair->key, cur->pair->val);
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cur = cur->next;
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}
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printf("]\n");
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}
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return;
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}
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/* Driver Code */
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int main() {
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/* 初始化哈希表 */
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hashMapChaining *map = newHashMapChaining();
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hashMapChaining *hashMap = initHashMapChaining();
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/* 添加操作 */
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// 在哈希表中添加键值对 (key, value)
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put(map, 12836, "小哈");
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put(map, 15937, "小啰");
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put(map, 16750, "小算");
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put(map, 13276, "小法");
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put(map, 10583, "小鸭");
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put(hashMap, 12836, "小哈");
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put(hashMap, 15937, "小啰");
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put(hashMap, 16750, "小算");
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put(hashMap, 13276, "小法");
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put(hashMap, 10583, "小鸭");
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printf("\n添加完成后,哈希表为\nKey -> Value\n");
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print(map);
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print(hashMap);
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/* 查询操作 */
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// 向哈希表输入键 key ,得到值 value
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const char *name = get(map, 13276);
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char *name = get(hashMap, 13276);
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printf("\n输入学号 13276 ,查询到姓名 %s\n", name);
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/* 删除操作 */
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// 在哈希表中删除键值对 (key, value)
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removeItem(map, 12836);
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printf("\n删除 12836 后,哈希表为\nKey -> Value\n");
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print(map);
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removeKey(hashMap, 12836);
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printf("\n删除学号 12836 后,哈希表为\nKey -> Value\n");
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print(hashMap);
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/* 释放哈希表空间 */
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freeHashMapChaining(hashMap);
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delHashMapChaining(map);
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return 0;
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}
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@ -94,6 +94,8 @@
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=== "C"
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```c title="hash_map_chaining.c"
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[class]{node}-[func]{}
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[class]{hashMapChaining}-[func]{}
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```
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