LeetCode 100. Same Tree

100. Same Tree

Difficulty: 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

Language: Java

/**
 * 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 || p.val != q.val) {
                  return false;
           }
            return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
     }
}