leetcode-129 Sum Root to Leaf Numbers

来源：互联网发布：网络上gp是什么意思编辑：程序博客网时间：2024/05/16 04:49

DFS的题目好像都是用递归

遇到递归的时候，把终止条件，各种条件想清楚就可以大胆写了，可以先举几个简单的例子帮助

<span style="font-family:Microsoft YaHei;font-size:14px;">/** * 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) {        if(root == NULL) return 0;        int sum = 0;        return helper(root,sum);    }    int helper(TreeNode *node,int sum){        if(node->left == NULL && node->right == NULL)            return sum * 10 + node->val;        int val = 0;        if(node->left != NULL)           val += helper(node->left,sum * 10 + node->val);        if(node->right != NULL)           val += helper(node->right,sum * 10 + node->val);        return val;    }};</span>

0 0