53. 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 && sum-root.val==0) return true;
        else return hasPathSum(root.left, sum-root.val) || hasPathSum(root.right, sum-root.val);
    }
}