Check whether the two Binary Search Trees are Identical or Not

Given the root nodes of the two binary search trees. The task is to print 1 if the two Binary Search Trees are identical else print 0. Two trees are identical if they are identical structurally and nodes have the same values.

Tree 1

Tree 2

In the above images, both Tree1 and Tree2 are identical.

To identify if two trees are identical, we need to traverse both trees simultaneously, and while traversing we need to compare data and children of the trees.



Below is the step by step algorithm to check if two BSTs are identical:

  1. If both trees are empty then return 1.
  2. Else If both trees are non -empty
    • Check data of the root nodes (tree1->data == tree2->data)
    • Check left subtrees recursively i.e., call sameTree(tree1->left_subtree, tree2->left_subtree)
    • Check right subtrees recursively i.e., call sameTree(tree1->right_subtree, tree2->right_subtree)
    • If the values returned in the above three steps are true then return 1.
  3. Else return 0 (one is empty and other is not).

Below is the implementation of the above approach:

C++

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// C++ program to check if two BSTs
// are identical
  
#include <iostream>
using namespace std;
  
// BST node
struct Node {
    int data;
    struct Node* left;
    struct Node* right;
};
  
// Utility function to create a new Node
struct Node* newNode(int data)
{
    struct Node* node = (struct Node*)
        malloc(sizeof(struct Node));
    node->data = data;
    node->left = NULL;
    node->right = NULL;
  
    return node;
}
  
// Function to perform inorder traversal
void inorder(Node* root)
{
    if (root == NULL)
        return;
  
    inorder(root->left);
  
    cout << root->data << " ";
  
    inorder(root->right);
}
  
// Function to check if two BSTs
// are identical
int isIdentical(Node* root1, Node* root2)
{
    // Check if both the trees are empty
    if (root1 == NULL && root2 == NULL)
        return 1;
    // If any one of the tree is non-empty
    // and other is empty, return false
    else if (root1 != NULL && root2 == NULL)
        return 0;
    else if (root1 == NULL && root2 != NULL)
        return 0;
    else { // Check if current data of both trees equal
        // and recursively check for left and right subtrees
        if (root1->data == root2->data && isIdentical(root1->left, root2->left)
            && isIdentical(root1->right, root2->right))
            return 1;
        else
            return 0;
    }
}
  
// Driver code
int main()
{
    struct Node* root1 = newNode(5);
    struct Node* root2 = newNode(5);
    root1->left = newNode(3);
    root1->right = newNode(8);
    root1->left->left = newNode(2);
    root1->left->right = newNode(4);
  
    root2->left = newNode(3);
    root2->right = newNode(8);
    root2->left->left = newNode(2);
    root2->left->right = newNode(4);
  
    if (isIdentical(root1, root2))
        cout << "Both BSTs are identical";
    else
        cout << "BSTs are not identical";
  
    return 0;
}

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Java














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// Java program to check if two BSTs 


// are identical 


class GFG 


{ 


  


// BST node 


static class Node  


{ 


    int data; 


    Node left; 


    Node right; 


}; 


  


// Utility function to create a new Node 


static Node newNode(int data) 


{ 


    Node node = new Node(); 


    node.data = data; 


    node.left = null; 


    node.right = null; 


  


    return node; 


} 


  


// Function to perform inorder traversal 


static void inorder(Node root) 


{ 


    if (root == null) 


        return; 


  


    inorder(root.left); 


  


    System.out.print(root.data + " "); 


  


    inorder(root.right); 


} 


  


// Function to check if two BSTs 


// are identical 


static int isIdentical(Node root1,  


                       Node root2) 


{ 


    // Check if both the trees are empty 


    if (root1 == null && root2 == null) 


        return 1; 


          


    // If any one of the tree is non-empty 


    // and other is empty, return false 


    else if (root1 != null &&  


             root2 == null) 


        return 0; 


    else if (root1 == null &&  


             root2 != null) 


        return 0; 


    else 


    {  


        // Check if current data of both trees equal 


        // and recursively check for left and right subtrees 


        if (root1.data == root2.data &&  


            isIdentical(root1.left, root2.left) == 1 &&  


            isIdentical(root1.right, root2.right) == 1) 


            return 1; 


        else


            return 0; 


    } 


} 


  


// Driver code 


public static void main(String[] args) 


{ 


    Node root1 = newNode(5); 


    Node root2 = newNode(5); 


    root1.left = newNode(3); 


    root1.right = newNode(8); 


    root1.left.left = newNode(2); 


    root1.left.right = newNode(4); 


  


    root2.left = newNode(3); 


    root2.right = newNode(8); 


    root2.left.left = newNode(2); 


    root2.left.right = newNode(4); 


  


    if (isIdentical(root1, root2)==1) 


        System.out.print("Both BSTs are identical"); 


    else


        System.out.print("BSTs are not identical"); 


} 


} 


  


// This code is contributed by 29AjayKumar 



















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Python3














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# Python3 program to contrcut all unique 


# BSTs for keys from 1 to n  


  


# Binary Tree Node  


""" A utility function to create a 


new BST node """


class newNode:  


  


    # Construct to create a newNode  


    def __init__(self, data):  


        self.data = data 


        self.left = None


        self.right = None


  


# Function to perform inorder traversal  


def inorder(root) : 


  


    if (root == None):  


        return


  


    inorder(root.left)  


  


    print(root.data, end = " ")  


  


    inorder(root.right)  


  


# Function to check if two BSTs  


# are identical  


def isIdentical(root1, root2) : 


  


    # Check if both the trees are empty  


    if (root1 == None and root2 == None) : 


        return 1


          


    # If any one of the tree is non-empty  


    # and other is empty, return false  


    elif (root1 != None and root2 == None) : 


        return 0


    elif (root1 == None and root2 != None) : 


        return 0


    else: # Check if current data of both trees  


          # equal and recursively check for left  


          # and right subtrees  


        if (root1.data == root2.data and 


            isIdentical(root1.left, root2.left)  


            and isIdentical(root1.right, root2.right)) : 


            return 1


        else: 


            return 0


      


# Driver Code  


if __name__ == '__main__': 


  


    root1 = newNode(5)  


    root2 = newNode(5)  


    root1.left = newNode(3)  


    root1.right = newNode(8)  


    root1.left.left = newNode(2)  


    root1.left.right = newNode(4)  


  


    root2.left = newNode(3)  


    root2.right = newNode(8)  


    root2.left.left = newNode(2)  


    root2.left.right = newNode(4)  


  


    if (isIdentical(root1, root2)):  


        print("Both BSTs are identical") 


    else: 


        print("BSTs are not identical") 


  


# This code is contributed by 


# Shubham Singh(SHUBHAMSINGH10) 



















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C#














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// C# program to check if two BSTs 


// are identical 


using System; 


  


class GFG 


{ 


  


// BST node 


class Node  


{ 


    public int data; 


    public Node left; 


    public Node right; 


}; 


  


// Utility function to create a new Node 


static Node newNode(int data) 


{ 


    Node node = new Node(); 


    node.data = data; 


    node.left = null; 


    node.right = null; 


  


    return node; 


} 


  


// Function to perform inorder traversal 


static void inorder(Node root) 


{ 


    if (root == null) 


        return; 


  


    inorder(root.left); 


  


    Console.Write(root.data + " "); 


  


    inorder(root.right); 


} 


  


// Function to check if two BSTs 


// are identical 


static int isIdentical(Node root1,  


                       Node root2) 


{ 


    // Check if both the trees are empty 


    if (root1 == null && root2 == null) 


        return 1; 


          


    // If any one of the tree is non-empty 


    // and other is empty, return false 


    else if (root1 != null &&  


             root2 == null) 


        return 0; 


    else if (root1 == null &&  


             root2 != null) 


        return 0; 


    else


    {  


        // Check if current data of both trees equal 


        // and recursively check for left and right subtrees 


        if (root1.data == root2.data &&  


            isIdentical(root1.left, root2.left) == 1 &&  


            isIdentical(root1.right, root2.right) == 1) 


            return 1; 


        else


            return 0; 


    } 


} 


  


// Driver code 


public static void Main(String[] args) 


{ 


    Node root1 = newNode(5); 


    Node root2 = newNode(5); 


    root1.left = newNode(3); 


    root1.right = newNode(8); 


    root1.left.left = newNode(2); 


    root1.left.right = newNode(4); 


  


    root2.left = newNode(3); 


    root2.right = newNode(8); 


    root2.left.left = newNode(2); 


    root2.left.right = newNode(4); 


  


    if (isIdentical(root1, root2) == 1) 


        Console.Write("Both BSTs are identical"); 


    else


        Console.Write("BSTs are not identical"); 


} 


} 


  


// This code is contributed by PrinciRaj1992 



















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Output:


Both BSTs are identical








    

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