# DIY: Validate the Binary Search Tree

Solve the interview question "Validate the Binary Search Tree" in this lesson.

We'll cover the following

## Problem statement

For this challenge, you are given an integer array. You have to implement the in_orderBST() function to validate whether the given integer array represents the in-order traversal of a valid binary search tree

### Constraints

• Nodes count of the binary search tree in the range [1, $10^4$].
• $-2^{31}$ <= Node.value <= $2^{31}$ - 1

### Input

The input of the in_orderBST() function is an integer array and its length. The following is an example input:

[8,12,15,21,24,32,45]


### Output

The following is the output of the in_orderBST() function, in case it fulfills the condition:

Valid BST


Otherwise, it outputs the following:

Not valid BST


## Coding exercise

Implement the in_orderBST(array,n) function, where array is an integer array that represents the in-order traversal of a binary search tree, and n is the given array’s length.

Level up your interview prep. Join Educative to access 70+ hands-on prep courses.