https://oj.leetcode.com/problems/path-sum/
/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean hasPathSum(TreeNode root, int sum) {
if(root==null) return false;
if(root.left==null&&root.right==null)
{
if(sum==root.val) return true; } return hasPathSum(root.left,sum-root.val)||hasPathSum(root.right,sum-root.val); }
}