添加 0039.组合总和.md C语言版本

problems/0039.组合总和.md

@@ -346,6 +346,60 @@ var combinationSum = function(candidates, target) {
 };
 ```
 
+C:
+```c
+int* path;
+int pathTop;
+int** ans;
+int ansTop;
+//记录每一个和等于target的path数组长度
+int* length;
+
+void backTracking(int target, int index, int* candidates, int candidatesSize, int sum) {
+    //若sum>=target就应该终止遍历
+    if(sum >= target) {
+        //若sum等于target，将当前的组合放入ans数组中
+        if(sum == target) {
+            int* tempPath = (int*)malloc(sizeof(int) * pathTop);
+            int j;
+            for(j = 0; j < pathTop; j++) {
+                tempPath[j] = path[j];
+            }
+            ans[ansTop] = tempPath;
+            length[ansTop++] = pathTop;
+        }
+        return ;
+    }
+
+    int i;
+    for(i = index; i < candidatesSize; i++) {
+        //将当前数字大小加入sum
+        sum+=candidates[i];
+        path[pathTop++] = candidates[i];
+        backTracking(target, i, candidates, candidatesSize, sum);
+        sum-=candidates[i];
+        pathTop--;
+    }
+}
+
+int** combinationSum(int* candidates, int candidatesSize, int target, int* returnSize, int** returnColumnSizes){
+    //初始化变量
+    path = (int*)malloc(sizeof(int) * 50);
+    ans = (int**)malloc(sizeof(int*) * 200);
+    length = (int*)malloc(sizeof(int) * 200);
+    ansTop = pathTop = 0;
+    backTracking(target, 0, candidates, candidatesSize, 0);
+
+    //设置返回的数组大小
+    *returnSize = ansTop;
+    *returnColumnSizes = (int*)malloc(sizeof(int) * ansTop);
+    int i;
+    for(i = 0; i < ansTop; i++) {
+        (*returnColumnSizes)[i] = length[i];
+    }
+    return ans;
+}
+```
 
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 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)