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Validate Binary Search Tree

Given the root of a binary tree (as a level-order array), determine if it is a valid binary search tree (BST).

A valid BST has:

Input:

2,1,3

Output:

True

Reasoning:

The input array 2,1,3 represents a binary tree with root node 2, left child 1, and right child 3.
We check the left subtree: since 1 is less than 2, it satisfies the BST condition.
We check the right subtree: since 3 is greater than 2, it satisfies the BST condition.
Both subtrees are valid BSTs (as they are single nodes with no children), so the entire tree is a valid binary search tree, resulting in an output of True.

Editor

Python 3.13.1

0/0

Run code to see test results.