leetcode 刷题之路 30 Path Sum

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.

判断二叉树根节点到叶子节点的路径和是否等于某一个数。

/** * 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)return false;if (root->left == NULL&&root->right == NULL){if (root->val == sum)return true;elsereturn false;}return hasPathSum(root->left, sum - root->val) || hasPathSum(root->right, sum - root->val);}};