Path Sum —— Leetcode

来源：互联网发布：淘宝来店提醒编辑：程序博客网时间：2024/05/16 19:53

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5             / \            4   8           /   / \          11  13  4         /  \      \        7    2      1

return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.

理解递归思想之后，代码变得很简单，第一次提交时候写错了下面的两点：

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    bool hasPathSum(TreeNode *root, int sum) {        if(root==NULL)  //1. if root is NULL            return false;        if(root->left==NULL && root->right==NULL && sum-root->val==0)   //2. sum-root->val==0            return true;        return hasPathSum(root->left, sum-root->val) || hasPathSum(root->right, sum-root->val);    }};

0 0