LeetCode——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.

中文：给定一二叉树和一个总和，判断此树是否有根到叶的路径上的值之和等于给定的总和的路径。

递归。

public boolean hasPathSum(TreeNode root, int sum) {
if (root == null)
return false;
int temp = sum - root.val;
if (temp == 0 && root.left == null && root.right == null)
return true;
return hasPathSum(root.left, temp) || hasPathSum(root.right, temp);
}