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.

简单的DFS的一题。

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {private:    int ans = 0;public:    int sumNumbers(TreeNode *root) {        if(root==NULL) return ans;        int c = 0;        solve(root,c);                return ans;    }        void solve(TreeNode *root,int &temp)    {        if(root->left == NULL && root->right==NULL)        {            ans = ans + temp*10 + root->val;            return;        }                temp = temp*10+root->val;        if(root->left) solve(root->left,temp);        if(root->right) solve(root->right,temp);        temp = (temp-root->val)/10;    }};