Fix unreleased memory error (#769)

* 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

* fix(codes/c): Fix space_complexity.c build error.

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

* feat(code/c): Update push_back and pop_back in vector.h

* styles(codes/c): Adjust  format.

* feat(codes/c): Add `interation.c ` `recursion.c` `simple_hash.c` `binary_search_edge.c` `binary_search_insertion.c` in C codes.

* fix(mylist.c): Fix `insert` function in `mylist.c`

https://github.com/krahets/hello-algo/discussions/32#discussioncomment-6974163

* fix(array.c): Fix unreleased memory error

---------

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

codes/c/chapter_array_and_linkedlist/array.c

@@ -108,5 +108,7 @@ int main() {
     int index = find(res, size, 3);
     printf("在 res 中查找元素 3 ，得到索引 = %d\n", index);
 
+    /* 释放内存 */
+    free(res);
     return 0;
 }