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 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:    int sumTravel(TreeNode* p,int sum){        if(!p->left&&!p->right) return sum*10+p->val;        int result=0;        if(p->left) result+= sumTravel(p->left,sum*10+p->val);        if(p->right) result+= sumTravel(p->right,sum*10+p->val);        return result;    }    int sumNumbers(TreeNode *root) {        if(!root) return 0;        return sumTravel(root,0);    }};