feat: Add C codes for the chapter backtracking (#593)

* 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

* feat(codes/c): Add part of the c code in the backtracking chapter

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

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

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

* style(codes/c): Adjust the format

* feat(codes/c): Add memory release in chapter_backtracking

* fix(codes/c): Fix memory release issue.

* style(codes/c): Update format and Merge duplicate code

* style(code/c): Change print format in preorder_traversal_iii_template.c

* Update preorder_traversal_iii_template.c

* Update permutations_i.c

* feat(codes/c): Remove myArray, use public vector.

* feat(codes/c): Add subset_sum_i_naive.c in C codes.

* feat(codes/c): Add permutations_i in CMakeLists.txt

* feat(codes/c): Update printf function in vector.h.

* feat(codes/c): Add subset_sum_i.c and subset_sum_ii.c

---------

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

codes/c/utils/common.h

@@ -21,6 +21,8 @@
 // hash table lib
 #include "uthash.h"
 
+#include "vector.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif

codes/c/utils/vector.h

@@ -0,0 +1,139 @@
+/**
+ * File: vector.h
+ * Created Time: 2023-07-13
+ * Author: Gonglja (glj0@outlook.com)
+ */
+
+#ifndef VECTOR_H
+#define VECTOR_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* 定义向量类型 */
+typedef struct vector {
+    int size;     // 当前向量的大小
+    int capacity; // 当前向量的容量
+    int depth;    // 当前向量的深度
+    void **data;  // 指向数据的指针数组
+} vector;
+
+/* 构造向量 */
+vector *newVector() {
+    vector *v = malloc(sizeof(vector));
+    v->size = 0;
+    v->capacity = 4;
+    v->depth = 1;
+    v->data = malloc(v->capacity * sizeof(void *));
+    return v;
+}
+
+/* 析构向量 */
+void delVector(vector *v) {
+    if (v) {
+        if (v->depth == 0) {
+            return;
+        } else if (v->depth == 1) {
+            for (int i = 0; i < v->size; i++) {
+                free(v->data[i]);
+            }
+            free(v);
+        } else {
+            for (int i = 0; i < v->size; i++) {
+                delVector(v->data[i]);
+            }
+            v->depth--;
+        }
+    }
+}
+
+/*  添加元素到向量尾部 */
+void vectorPushback(vector *v, void *elem) {
+    if (v->size == v->capacity) {
+        v->capacity *= 2;
+        v->data = realloc(v->data, v->capacity * sizeof(void *));
+    }
+    v->data[v->size++] = elem;
+}
+
+/* 从向量尾部弹出元素 */
+void vectorPopback(vector *v) {
+    if (v->size != 0) {
+        v->size--;
+    }
+}
+
+/* 清空向量 */
+void vectorClear(vector *v) {
+    delVector(v);
+    v->size = 0;
+    v->capacity = 4;
+    v->depth = 1;
+    v->data = malloc(v->capacity * sizeof(void *));
+}
+
+/* 获取向量的大小 */
+int vectorSize(vector *v) {
+    return v->size;
+}
+
+/* 获取向量的尾元素 */
+void *vectorBack(vector *v) {
+    return v->data[v->size];
+}
+
+/* 获取向量的头元素 */
+void *vectorFront(vector *v) {
+    return v->data[0];
+}
+
+/* 打印函数， 需传递一个打印变量的函数进来 */
+/* 当前仅支持打印深度为 1 的 vector*/
+void printVector(vector *v, void (*printFunc)(vector *v, void *p)) {
+    if (v) {
+        if (v->depth == 0) {
+            return;
+        } else if (v->depth == 1) {
+            for (int i = 0; i < v->size; i++) {
+				if (i == 0) {
+					printf("[");
+				} else if (i == v->size-1) {
+					printFunc(v, v->data[i]);
+					printf("]\r\n");
+					break;
+				}
+				printFunc(v, v->data[i]);
+				printf(",");
+            }
+        } else {
+            for (int i = 0; i < v->size; i++) {
+                printVector(v->data[i], printFunc);
+            }
+            v->depth--;
+        }
+    }
+}
+
+/* 当前仅支持打印深度为 2 的 vector */
+void printVectorMatrix(vector *vv, void (*printFunc)(vector *v, void *p)) {
+	printf("[\n");
+	for (int i = 0; i < vv->size; i++) {
+		vector *v = (vector *)vv->data[i];
+		printf("  [");
+		for (int j = 0; j < v->size; j++) {
+			printFunc(v, v->data[j]);
+			if (j != v->size -1)
+				printf(",");
+		}
+		printf("],");
+		printf("\n");
+	}
+	printf("]\n");
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // VECTOR_H