100. 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 class Solution {
11     public boolean isSameTree(TreeNode p, TreeNode q) {
12         if( p == null && q == null ){
13             return true;
14         }else if( (p == null && q != null) || (p != null && q == null)){
15             return false;
16         }
17         
18         if(p.val != q.val ){
19             return false;
20         }else{
21             return isSameTree(p.left, q.left)&&isSameTree(p.right, q.right);
22         }
23         
24         
25     }
26 }