添加 0129.求根到叶子节点数字之和.md C语言解法

problems/0129.求根到叶子节点数字之和.md

@@ -289,7 +289,33 @@ var sumNumbers = function(root) {
 };
 ```
 
+C:
+```c
+//sum记录总和
+int sum;
+void traverse(struct TreeNode *node, int val) {
+    //更新val为根节点到当前节点的和
+    val = val * 10 + node->val;
+    //若当前节点为叶子节点，记录val
+    if(!node->left && !node->right) {
+        sum+=val;
+        return;
+    }
+    //若有左/右节点，遍历左/右节点
+    if(node->left) 
+        traverse(node->left, val);
+    if(node->right)
+        traverse(node->right, val);
+}
 
+int sumNumbers(struct TreeNode* root){
+    sum = 0;
+    
+    traverse(root, 0);
+
+    return sum;
+}
+```
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>