添加 0047.全排列II.md C语言版本

problems/0047.全排列II.md

@@ -323,5 +323,76 @@ func permuteUnique(_ nums: [Int]) -> [[Int]] {
 }
 ```
 
+### C
+```c
+//临时数组
+int *path;
+//返回数组
+int **ans;
+int *used;
+int pathTop, ansTop;
+
+//拷贝path到ans中
+void copyPath() {
+    int *tempPath = (int*)malloc(sizeof(int) * pathTop);
+    int i;
+    for(i = 0; i < pathTop; ++i) {
+        tempPath[i] = path[i];
+    }
+    ans[ansTop++] = tempPath;
+}
+
+void backTracking(int* used, int *nums, int numsSize) {
+    //若path中元素个数等于numsSize，将path拷贝入ans数组中
+    if(pathTop == numsSize)
+        copyPath();
+    int i;
+    for(i = 0; i < numsSize; i++) {
+        //若当前元素已被使用
+        //或前一位元素与当前元素值相同但并未被使用
+        //则跳过此分支
+        if(used[i] || (i != 0 && nums[i] == nums[i-1] && used[i-1] == 0))
+            continue;
+
+        //将当前元素的使用情况设为True
+        used[i] = 1;
+        path[pathTop++] = nums[i];
+        backTracking(used, nums, numsSize);
+        used[i] = 0;
+        --pathTop;
+    }
+}
+
+int cmp(void* elem1, void* elem2) {
+    return *((int*)elem1) - *((int*)elem2);
+}
+
+int** permuteUnique(int* nums, int numsSize, int* returnSize, int** returnColumnSizes){
+    //排序数组
+    qsort(nums, numsSize, sizeof(int), cmp);
+    //初始化辅助变量
+    pathTop = ansTop = 0;
+    path = (int*)malloc(sizeof(int) * numsSize);
+    ans = (int**)malloc(sizeof(int*) * 1000);
+    //初始化used辅助数组
+    used = (int*)malloc(sizeof(int) * numsSize);
+    int i;
+    for(i = 0; i < numsSize; i++) {
+        used[i] = 0;
+    }
+
+    backTracking(used, nums, numsSize);
+
+    //设置返回的数组的长度
+    *returnSize = ansTop;
+    *returnColumnSizes = (int*)malloc(sizeof(int) * ansTop);
+    int z;
+    for(z = 0; z < ansTop; z++) {
+        (*returnColumnSizes)[z] = numsSize;
+    }
+    return ans;
+}
+```
+
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