feat: Add C codes for bucket sort, heap sort, selection sort, binary search edge (#525)

* fix(codes/cpp): Memory leak fix: the space was not freed when pop removed the element.

* fix(codes/cpp): Fix access error when printArray(arr, 0)

* Update PrintUtil.hpp

* fix(codes/c): Fix some errors of cmake build

* feat(codes/c): Add hashing_search.c

* styles(codes/c): Modify function description

* styles(codes/c): Modify binary_search.c code style

* fix(codes/c): Fix the problem in binary_tree_bfs.c and the problem that the memory is not released.

* feat: Add preorder_traversal_i_compact.c

* feat(codes/c): Add head_sort.c

* feat(codes/c): Add bucket_sort.c

* feat(codes/c): Add binary_search_edge.c

* fix(codes/c): Add programs that are not managed by cmake (c code)

* feat(codes/c): Add selection_sort.c

* style(codes/c): Change swap in selection_sort.c to `selectionSort`

* styles(codes/c): Change style.

* fix(codes/c): Fix some formatting errors and temporarily remove backtracking chapters

---------

Co-authored-by: Yudong Jin <krahets@163.com>

codes/c/CMakeLists.txt

@@ -12,4 +12,5 @@ add_subdirectory(chapter_heap)
 add_subdirectory(chapter_hashing)
 add_subdirectory(chapter_tree)
 add_subdirectory(chapter_searching)
-add_subdirectory(chapter_sorting)
+add_subdirectory(chapter_sorting)
+add_subdirectory(chapter_backtracking)

codes/c/chapter_searching/CMakeLists.txt

@@ -1,2 +1,5 @@
 add_executable(binary_search binary_search.c)
-add_executable(two_sum two_sum.c)
+add_executable(two_sum two_sum.c)
+add_executable(binary_search_edge binary_search_edge.c)
+add_executable(hashing_search hashing_search.c)
+add_executable(linear_search linear_search.c)

codes/c/chapter_searching/binary_search_edge.c

@@ -0,0 +1,59 @@
+/**
+ * File: binary_search_edge.c
+ * Created Time: 2023-05-31
+ * Author: Gonglja (glj0@outlook.com)
+ */
+
+#include "../utils/common.h"
+
+
+/* 二分查找最左一个元素 */
+int binarySearchLeftEdge(int *nums, int size, int target) {
+    int i = 0, j = size - 1; // 初始化双闭区间 [0, n-1]
+    while (i <= j) {
+        int m = i + (j - i) / 2; // 计算中点索引 m
+        if (nums[m] < target)
+            i = m + 1; // target 在区间 [m+1, j] 中
+        else if (nums[m] > target)
+            j = m - 1; // target 在区间 [i, m-1] 中
+        else
+            j = m - 1; // 首个小于 target 的元素在区间 [i, m-1] 中
+    }
+    if (i == size || nums[i] != target)
+        return -1; // 未找到目标元素，返回 -1
+    return i;
+}
+
+/* 二分查找最右一个元素 */
+int binarySearchRightEdge(int *nums, int size, int target) {
+    int i = 0, j = size - 1; // 初始化双闭区间 [0, n-1]
+    while (i <= j) {
+        int m = i + (j - i) / 2; // 计算中点索引 m
+        if (nums[m] < target)
+            i = m + 1; // target 在区间 [m+1, j] 中
+        else if (nums[m] > target)
+            j = m - 1; // target 在区间 [i, m-1] 中
+        else
+            i = m + 1; // 首个大于 target 的元素在区间 [m+1, j] 中
+    }
+    if (j < 0 || nums[j] != target)
+        return -1; // 未找到目标元素，返回 -1
+    return j;
+}
+
+/* Driver Code */
+int main() {
+    int target = 6;
+    int nums[] = {1, 3, 6, 6, 6, 6, 6, 10, 12, 15};
+    int size = sizeof(nums) / sizeof(nums[0]);
+
+    // 二分查找最左一个元素
+    int indexLeft = binarySearchLeftEdge(nums, size, target);
+    printf("数组中最左一个元素 6 的索引 = %d\n", indexLeft);
+
+    // 二分查找最右一个元素
+    int indexRight = binarySearchRightEdge(nums, size, target);
+    printf("数组中最右一个元素 6 的索引 = %d\n", indexRight);
+
+    return 0;
+}

codes/c/chapter_sorting/CMakeLists.txt

@@ -4,3 +4,6 @@ add_executable(quick_sort quick_sort.c)
 add_executable(counting_sort counting_sort.c)
 add_executable(radix_sort radix_sort.c)
 add_executable(merge_sort merge_sort.c)
+add_executable(heap_sort heap_sort.c)
+add_executable(bucket_sort bucket_sort.c)
+add_executable(selection_sort selection_sort.c)

codes/c/chapter_sorting/bucket_sort.c

@@ -0,0 +1,82 @@
+/**
+ * File: bucket_sort.c
+ * Created Time: 2023-05-30
+ * Author: Gonglja (glj0@outlook.com)
+ */
+
+#include "../utils/common.h"
+
+#define ARRAY_SIZE 10
+
+/* 比较两个浮点数的大小 */
+int compare_float(const void *a, const void *b) {
+    float fa = *(const float *)a;
+    float fb = *(const float *)b;
+    return (fa > fb) - (fa < fb);
+}
+
+/* 交换两个浮点数 */
+void swap(float *a, float *b) {
+    float tmp = *a;
+    *a = *b;
+    *b = tmp;
+}
+
+/* 桶排序 */
+void bucketSort(float nums[], int size) {
+    // 初始化 k = n/2 个桶，预期向每个桶分配 2 个元素
+    int k = size / 2;
+    float **buckets = calloc(k, sizeof(float *));
+    for (int i = 0; i < k; i++) {
+        // 每个桶最多可以分配 k 个元素
+        buckets[i] = calloc(ARRAY_SIZE, sizeof(float));
+    }
+
+    // 1. 将数组元素分配到各个桶中
+    for (int i = 0; i < size; i++) {
+        // 输入数据范围 [0, 1)，使用 num * k 映射到索引范围 [0, k-1]
+        int bucket_idx = nums[i] * k;
+        int j = 0;
+        // 如果桶中有数据且数据小于当前值 nums[i], 要将其放到当前桶的后面，相当于 cpp 中的 push_back
+        while (buckets[bucket_idx][j] > 0 && buckets[bucket_idx][j] < nums[i]) {
+            j++;
+        }
+        float temp = nums[i];
+        while (j < ARRAY_SIZE && buckets[bucket_idx][j] > 0) {
+            swap(&temp, &buckets[bucket_idx][j]);
+            j++;
+        }
+        buckets[bucket_idx][j] = temp;
+    }
+
+    // 2. 对各个桶执行排序
+    for (int i = 0; i < k; i++) {
+        qsort(buckets[i], ARRAY_SIZE, sizeof(float), compare_float);
+    }
+
+    // 3. 遍历桶合并结果
+    for (int i = 0, j = 0; j < k; j++) {
+        for (int l = 0; l < ARRAY_SIZE; l++) {
+            if (buckets[j][l] > 0) {
+                nums[i++] = buckets[j][l];
+            }
+        }
+    }
+
+    // 释放上述分配的内存
+    for (int i = 0; i < k; i++) {
+        free(buckets[i]);
+    }
+    free(buckets);
+}
+
+/* Driver Code */
+int main() {
+    // 设输入数据为浮点数，范围为 [0, 1)
+    float nums[ARRAY_SIZE] = {0.49f, 0.96f, 0.82f, 0.09f, 0.57f, 0.43f, 0.91f, 0.75f, 0.15f, 0.37f};
+    bucketSort(nums, ARRAY_SIZE);
+    printf("桶排序完成后 nums = ");
+    printArrayFloat(nums, ARRAY_SIZE);
+
+    return 0;
+}

codes/c/chapter_sorting/heap_sort.c

@@ -0,0 +1,60 @@
+/**
+ * File: heap_sort.c
+ * Created Time: 2023-05-30
+ * Author: Gonglja (glj0@outlook.com)
+ */
+
+#include "../utils/common.h"
+
+/* 堆的长度为 n ，从节点 i 开始，从顶至底堆化 */
+void siftDown(int nums[], int n, int i) {
+    while (1) {
+        // 判断节点 i, l, r 中值最大的节点，记为 ma
+        int l = 2 * i + 1;
+        int r = 2 * i + 2;
+        int ma = i;
+        if (l < n && nums[l] > nums[ma])
+            ma = l;
+        if (r < n && nums[r] > nums[ma])
+            ma = r;
+        // 若节点 i 最大或索引 l, r 越界，则无需继续堆化，跳出
+        if (ma == i) {
+            break;
+        }
+        // 交换两节点
+        int temp = nums[i];
+        nums[i] = nums[ma];
+        nums[ma] = temp;
+        // 循环向下堆化
+        i = ma;
+    }
+}
+
+/* 堆排序 */
+void heapSort(int nums[], int n) {
+    // 建堆操作：堆化除叶节点以外的其他所有节点
+    for (int i = n / 2 - 1; i >= 0; --i) {
+        siftDown(nums, n, i);
+    }
+    // 从堆中提取最大元素，循环 n-1 轮
+    for (int i = n - 1; i > 0; --i) {
+        // 交换根节点与最右叶节点（即交换首元素与尾元素）
+        int tmp = nums[0];
+        nums[0] = nums[i];
+        nums[i] = tmp;
+        // 以根节点为起点，从顶至底进行堆化
+        siftDown(nums, i, 0);
+    }
+}
+
+/* Driver Code */
+int main() {
+    int nums[] = {4, 1, 3, 1, 5, 2};
+    int n = sizeof(nums) / sizeof(nums[0]);
+
+    heapSort(nums, n);
+    printf("堆排序完成后 nums = ");
+    printArray(nums, n);
+
+    return 0;
+}

codes/c/chapter_sorting/selection_sort.c

@@ -0,0 +1,37 @@
+/**
+ * File: selection_sort.c
+ * Created Time: 2023-05-31
+ * Author: Gonglja (glj0@outlook.com)
+ */
+
+#include "../utils/common.h"
+
+/* 选择排序 */
+void selectionSort(int nums[], int n) {
+    // 外循环：未排序区间为 [i, n-1]
+    for (int i = 0; i < n - 1; i++) {
+        // 内循环：找到未排序区间内的最小元素
+        int k = i;
+        for (int j = i + 1; j < n; j++) {
+            if (nums[j] < nums[k])
+                k = j;  // 记录最小元素的索引
+        }
+        // 将该最小元素与未排序区间的首个元素交换
+        int temp = nums[i];
+        nums[i] = nums[k];
+        nums[k] = temp;
+    }
+}
+
+/* 主函数 */
+int main() {
+    int nums[] = {4, 1, 3, 1, 5, 2};
+    int n = sizeof(nums) / sizeof(nums[0]);
+
+    selectionSort(nums, n);
+
+    printf("选择排序完成后 nums = ");
+    printArray(nums, n);
+
+    return 0;
+}

codes/c/utils/print_util.h

@@ -39,6 +39,27 @@ static void printArray(int arr[], int size) {
     }
 }
 
+/* Print an Array */
+static void printArrayFloat(float arr[], int size) {
+    printf("[");
+    if (arr != NULL && size != 0) {
+        for (int i = 0; i < size - 1; i++) {
+            if (arr[i] != INT_MAX) {
+                printf("%.2f, ", arr[i]);
+            } else {
+                printf("NULL, ");
+            }
+        }
+        if (arr[size - 1] != INT_MAX) {
+            printf("%.2f]\n", arr[size - 1]);
+        } else {
+            printf("NULL]\n");
+        }
+    } else {
+        printf("]");
+    }
+}
+
 /* Print a linked list */
 static void printLinkedList(ListNode *node) {
     if (node == NULL) {