Same Tree

Easy
Given two binary trees, write a function to check if they are the same or not.
Two binary trees are considered the same if they are structurally identical and the nodes have the same value.
Example 1:
Input:
1 1
/ \ / \
2 3 2 3
[1,2,3], [1,2,3]
Output:
true
Example 2:
Input:
1 1
/ \
2 2
[1,2], [1,null,2]
Output:
false
Example 3:
Input:
1 1
/ \ / \
2 1 1 2
[1,2,1], [1,1,2]
Output:
false

Solution

Recursion - check node val, left, right subtree
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {
if (p == null && q == null) {
return true;
}
if (p == null || q == null) {
return false;
}
return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}
}