[129]Sum Root to Leaf Numbers

【题目描述】

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.

【思路】

用递归实现深搜就可以了，一次AC。

【代码】

/** * 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:    vector<int> ans;       void dfs(TreeNode* root,int sum){        if(root->left==NULL&&root->right==NULL) ans.push_back(sum*10+root->val);         if(root->left!=NULL) dfs(root->left,sum*10+root->val);        if(root->right!=NULL) dfs(root->right,sum*10+root->val);    }    int sumNumbers(TreeNode* root) {       int ret=0;       if(root==NULL) return 0;       dfs(root,0);       for(int i=0;i<ans.size();i++){           ret+=ans[i];       }       return ret;    }};