/**
 * Definition for a binary tree node.
 * 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) return root.val == sum;
    return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
  }
}

add path-sum solution