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 number 123.

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 binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:void dfs(int &sum, int num, TreeNode *root){    if(root==NULL)return;    num+=root->val;    if(root->left==NULL&&root->right==NULL)    {        sum+=num;        return;    }    if(root->left)dfs(sum, 10*num, root->left);    if(root->right)dfs(sum, 10*num, root->right);}    int sumNumbers(TreeNode *root) {        int sum=0;        int num=0;        dfs(sum, num, root);        return sum;    }};