Valid BST from Preorder

Asked in:
Unbxd Inc.

Problem Description

You are given a preorder traversal A, of a Binary Search Tree.

Find if it is a valid preorder traversal of a BST.

Note: Binary Search Tree by definition has distinct keys and duplicates in binary search tree are not allowed.

Problem Constraints

1 <= A[i] <= 10⁶

1 <= |A| <= 10⁵

Input Format

First and only argument is an integer array A denoting the pre-order traversal.

Output Format

Return an integer:

0 : Impossible preorder traversal of a BST

1 : Possible preorder traversal of a BST

Example Input

Input 1:

A = [7, 7, 10, 10, 9, 5, 2, 8]

Example Output

Output 1:

NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a question? Checkout Sample Codes for more details.

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Asked In:

Unbxd Inc.

Valid BST from Preorder

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