fix(lang: c, chapters: searching, sorting): Some serious errors (#1531)

* fix: correct hash table insertion

* Use a pointer to a pointer instead of a single pointer in the insert function, ensuring proper updates to the hash table
* Bug fixes: This fixes issues with empty results.

* fix: correct issues in radix sort

* Replaced loop-based array copy with memcpy to ensure efficient memory copying in countingSortDigit
* Fixed a bug in radixSort where the maximum value search loop skipped the last element
* Bug fix: Ensures all elements are checked when determining the maximum value in the array

* perf: improve memory management by adding explicit memory release

* revert: Revert to using the old loop override array method and drop specific api's like memcpy.

codes/c/chapter_searching/two_sum.c

@@ -37,12 +37,12 @@ HashTable *find(HashTable *h, int key) {
 }
 
 /* 哈希表元素插入 */
-void insert(HashTable *h, int key, int val) {
-    HashTable *t = find(h, key);
+void insert(HashTable **h, int key, int val) {
+    HashTable *t = find(*h, key);
     if (t == NULL) {
         HashTable *tmp = malloc(sizeof(HashTable));
         tmp->key = key, tmp->val = val;
-        HASH_ADD_INT(h, key, tmp);
+        HASH_ADD_INT(*h, key, tmp);
     } else {
         t->val = val;
     }
@@ -59,7 +59,7 @@ int *twoSumHashTable(int *nums, int numsSize, int target, int *returnSize) {
             *returnSize = 2;
             return res;
         }
-        insert(hashtable, nums[i], i);
+        insert(&hashtable, nums[i], i);
     }
     *returnSize = 0;
     return NULL;
@@ -83,4 +83,4 @@ int main() {
     printArray(res, returnSize);
 
     return 0;
-}
+}

codes/c/chapter_sorting/counting_sort.c

@@ -65,6 +65,7 @@ void countingSort(int nums[], int size) {
     // 使用结果数组 res 覆盖原数组 nums
     memcpy(nums, res, size * sizeof(int));
     // 5. 释放内存
+    free(res);
     free(counter);
 }
 

codes/c/chapter_sorting/radix_sort.c

@@ -16,6 +16,7 @@ int digit(int num, int exp) {
 void countingSortDigit(int nums[], int size, int exp) {
     // 十进制的位范围为 0~9 ，因此需要长度为 10 的桶数组
     int *counter = (int *)malloc((sizeof(int) * 10));
+    memset(counter, 0, sizeof(int) * 10); // 初始化为 0 以支持后续内存释放
     // 统计 0~9 各数字的出现次数
     for (int i = 0; i < size; i++) {
         // 获取 nums[i] 第 k 位，记为 d
@@ -39,13 +40,16 @@ void countingSortDigit(int nums[], int size, int exp) {
     for (int i = 0; i < size; i++) {
         nums[i] = res[i];
     }
+    // 释放内存
+    free(res);
+    free(counter);
 }
 
 /* 基数排序 */
 void radixSort(int nums[], int size) {
     // 获取数组的最大元素，用于判断最大位数
     int max = INT32_MIN;
-    for (size_t i = 0; i < size - 1; i++) {
+    for (int i = 0; i < size; i++) {
         if (nums[i] > max) {
             max = nums[i];
         }