Path Sum

 1 public class Solution {
 2     public boolean hasPathSum(TreeNode root, int sum) {
 3         // IMPORTANT: Please reset any member data you declared, as
 4         // the same Solution instance will be reused for each test case.
 5         if(root == null)
 6             return false;
 7         boolean[] result = new boolean[1];
 8         traversal(root, sum, result);
 9         return result[0];
10     }
11     
12     private void traversal(TreeNode root, int sum, boolean[] result)
13     {
14         if(root.left == null && root.right == null){
15             if(sum == root.val)
16                 result[0] = true;;
17             return;}
18         if(root.left != null)
19             traversal(root.left, sum - root.val, result);
20         if(root.right != null)
21             traversal(root.right, sum - root.val, result);
22     }
23 }