100 Same Tree.java

// Given the roots of two binary trees p and q, 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: p = [1,2,3], q = [1,2,3]
// Output: true

// Example 2:
// Input: p = [1,2], q = [1,null,2]
// Output: false

// Example 3:
// Input: p = [1,2,1], q = [1,1,2]
// Output: false
 
// Constraints:
// The number of nodes in both trees is in the range [0, 100].
// -104 <= Node.val <= 104

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */

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);
    }
}