SameTree.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 */

/**
 * 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 SameTree {
	
    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);
    }
	

}