129. 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.

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/** * 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 tempsum)    {        if(root->left==NULL && root->right==NULL)        {            sum+=tempsum;            return ;        }        if(root->left)        dfs(root->left,sum,tempsum*10+root->left->val);        if(root->right)        dfs(root->right,sum,tempsum*10+root->right->val);        return ;    }    int sumNumbers(TreeNode* root) {        int sum=0;        if(root==NULL) return sum;        dfs(root,sum,root->val);        return sum;    }};