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 && root.val == sum) return true;        return hasPathSum(root.right, sum-root.val) || hasPathSum(root.left, sum-root.val);    }}