diff --git a/problems/0090.子集II.md b/problems/0090.子集II.md
index 6dc631de..ff5eb14d 100644
--- a/problems/0090.子集II.md
+++ b/problems/0090.子集II.md
@@ -279,6 +279,74 @@ var subsetsWithDup = function(nums) {
 
 ```
 
+C:
+```c
+int* path;
+int pathTop;
+int** ans;
+int ansTop;
+//负责存放二维数组中每个数组的长度
+int* lengths;
+//快排cmp函数
+int cmp(const void* a, const void* b) {
+    return *((int*)a) - *((int*)b);
+}
+
+//复制函数，将当前path中的元素复制到ans中。同时记录path长度
+void copy() {
+    int* tempPath = (int*)malloc(sizeof(int) * pathTop);
+    int i;
+    for(i = 0; i < pathTop; i++) {
+        tempPath[i] = path[i];
+    }
+    ans = (int**)realloc(ans, sizeof(int*) * (ansTop + 1));
+    lengths[ansTop] = pathTop;
+    ans[ansTop++] = tempPath;
+}
+
+void backTracking(int* nums, int numsSize, int startIndex, int* used) {
+    //首先将当前path复制
+    copy();
+    //若startIndex大于数组最后一位元素的位置，返回
+    if(startIndex >= numsSize)
+        return ;
+    
+    int i;
+    for(i = startIndex; i < numsSize; i++) {
+        //对同一树层使用过的元素进行跳过
+        if(i > 0 && nums[i] ==  nums[i-1] && used[i-1] == false) 
+            continue;
+        path[pathTop++] = nums[i];
+        used[i] = true;
+        backTracking(nums, numsSize, i + 1, used);
+        used[i] = false;
+        pathTop--;
+    }
+}
+
+int** subsetsWithDup(int* nums, int numsSize, int* returnSize, int** returnColumnSizes){
+    //声明辅助变量
+    path = (int*)malloc(sizeof(int) * numsSize);
+    ans = (int**)malloc(0);
+    lengths = (int*)malloc(sizeof(int) * 1500);
+    int* used = (int*)malloc(sizeof(int) * numsSize);
+    pathTop = ansTop = 0;
+
+    //排序后查重才能生效
+    qsort(nums, numsSize, sizeof(int), cmp);
+    backTracking(nums, numsSize, 0, used);
+
+    //设置一维数组和二维数组的返回大小
+    *returnSize = ansTop;
+    *returnColumnSizes = (int*)malloc(sizeof(int) * ansTop);
+    int i;
+    for(i = 0; i < ansTop; i++) {
+        (*returnColumnSizes)[i] = lengths[i];
+    }
+    return ans;
+}
+```
+
 
 
 -----------------------