添加 0216.组合总和II.md C语言版本

problems/0216.组合总和III.md

@@ -392,7 +392,63 @@ var combinationSum3 = function(k, n) {
 };
 ```
 
+C:
+```c
+int* path;
+int pathTop;
+int** ans;
+int ansTop;
+int getPathSum() {
+    int i;
+    int sum = 0;
+    for(i = 0; i < pathTop; i++) {
+        sum += path[i];
+    }
+    return sum;
+}
 
+void backtracking(int targetSum, int k, int sum, int startIndex) {
+    if(pathTop == k) {
+        if(sum == targetSum) {
+            int* tempPath = (int*)malloc(sizeof(int) * k);
+            int j;
+            for(j = 0; j < k; j++) 
+                tempPath[j] = path[j];
+            ans[ansTop++] = tempPath;
+        }
+        // 如果path.size() == k 但sum != targetSum 直接返回
+        return;
+    }
+    int i;
+    //从startIndex开始遍历，一直遍历到9
+    for (i = startIndex; i <= 9; i++) {
+        sum += i; // 处理
+        path[pathTop++] = i; // 处理
+        backtracking(targetSum, k, sum, i + 1); // 注意i+1调整startIndex
+        sum -= i; // 回溯
+        pathTop--;; // 回溯
+    }
+}
+
+int** combinationSum3(int k, int n, int* returnSize, int** returnColumnSizes){
+    //初始化辅助变量
+    path = (int*)malloc(sizeof(int) * k);
+    ans = (int**)malloc(sizeof(int*) * 20);
+    pathTop = ansTop = 0;
+
+    backtracking(n, k, 0, 1);
+
+    //设置返回的二维数组中元素个数为ansTop
+    *returnSize = ansTop;
+    //设置二维数组中每个元素个数的大小为k
+    *returnColumnSizes = (int*)malloc(sizeof(int) * ansTop);
+    int i;
+    for(i = 0; i < ansTop; i++) {
+        (*returnColumnSizes)[i] = k;
+    }
+    return ans;
+}
+```
 
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 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)