Added solution to leetcode#129

Author: ganm0

leetcode/cpp/Tree/129.cpp

@@ -0,0 +1,30 @@
+//Sum root to leaf numbers
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    int dfs(int parent, TreeNode* root){
+        int cur = parent*10+root->val;
+        int sum = 0;
+        if(root->left == NULL && root->right == NULL)
+            return cur;
+        if(root->left!=NULL)
+            sum = dfs(cur,root->left);
+        if(root->right!=NULL)
+            sum+=dfs(cur,root->right);
+        return sum;
+    }
+    int sumNumbers(TreeNode* root) {
+        if(root == NULL)
+            return 0;
+        return dfs(0,root);
+    }
+};