LeetCode - Same Tree

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

Solution:

 1 /**

 2  * Definition for binary tree

 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 r1, TreeNode r2) {

12         // Start typing your Java solution below

13         // DO NOT write main() function

14         if(r1 == null && r2 == null) 

15             return true;

16         if(r1 == null || r2 == null)

17             return false;

18         if(r1.val != r2.val)

19             return false;

20         return isSameTree(r1.left, r2.left) && isSameTree(r1.right, r2.right);

21     }

22 }