C++ Program to Check if a Binary Tree is a BST

Here, You will learn the concept of “C++ Program to Check if a Binary Tree is a BST”. Shall we try to do this task below? Let’s move.

Source Code

/*
* C++ Program to Check if a Binary Tree is a BST
*/
#include <iostream>
#include <cstdlib>
#include <climits>
using namespace std;

/*
* Node Declaration
*/
struct node
{
int data;
node* left;
node* right;
};

int isBSTUtil(node* node, int min, int max);

/*
* Returns true if the given tree is a binary search tree
*/
int isBST(node* node)
{
return(isBSTUtil(node, INT_MIN, INT_MAX));
}

/*
* Returns true if the given tree is a BST and its
* values are >= min and <= max.
*/
int isBSTUtil(struct node* node, int min, int max)
{
if (node==NULL)
return 1;
if (node->data < min || node->data > max)
return 0;
return isBSTUtil(node->left, min, node->data - 1) &&
isBSTUtil(node->right, node->data + 1, max);
}

/*
* allocates a new node with the data and NULL left and right pointers.
*/
node* newNode(int data)
{
node* nod = new node;
nod->data = data;
nod->left = NULL;
nod->right = NULL;
return nod;
}

/*
* Main
*/
int main()
{
node *root = newNode(4);
root->left = newNode(2);
root->right = newNode(5);
root->left->left = newNode(1);
root->left->right = newNode(3);
if (isBST(root))
cout<<"The Given Binary Tree is a BST"<<endl;
else
cout<<"The Given Binary Tree is not a BST"<<endl;
return 0;
}

Final Words 