Same Tree

 1 /**
 2  * Definition for a binary tree node.
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public boolean isSameTree(TreeNode p, TreeNode q) {
12         if (p == null && q == null) {
13             return true;
14         }
15         if (p == null || q == null) {
16             return false; 
17         }
18         if (p.val != q.val) {
19             return false;
20         }
21         return isSameTree(p.left, q.left) && isSameTree(p.right,q.right);
22         
23     }
24 }