[Leetcode]Sum Root to Leaf Numbers

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

An example is the root-to-leaf path 1->2->3 which represents the number123.

Find the total sum of all root-to-leaf numbers.

For example,

    1   / \  2   3

The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.

Return the sum = 12 + 13 = 25.

/** * 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:    void dfs(TreeNode* root,int& sum,int path){        if(!root)return;        if(!root->left&&!root->right){ //find one path            sum += path*10+root->val;            return;        }        dfs(root->left,sum,path*10+root->val);        dfs(root->right,sum,path*10+root->val);    }    int sumNumbers(TreeNode* root) {        int sum = 0;        dfs(root,sum,0);        return sum;    }};