leetcode—sum root to leaf number

题目如下：

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.

解题思路：

一个带有记录功能的DFS，随时记录当前数字，当前和，返回即可

代码如下：

/** * 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 sumNumbers(TreeNode *root) { // Start typing your C/C++ solution below // DO NOT write int main() function int sum = 0; int curNumber = 0; sumNumbers_my(root,curNumber,sum); return sum; } void sumNumbers_my(TreeNode *root,int &curNumber,int &sum) { if(root == NULL)return; curNumber = curNumber*10+root->val; int curNumber_bk = curNumber; if(root ->left== NULL&&root->right ==NULL) { sum+= curNumber;return; } sumNumbers_my(root->left,curNumber,sum); curNumber = curNumber_bk; sumNumbers_my(root->right,curNumber,sum); return; } };