Validate Binary Search Tree

Problem

Return true if the binary tree satisfies strict BST ordering. Input is a complete-index array with nulls.

Examples

Example 1

Input: [2,1,3]

Output: true

Example 2

Input: [5,1,4,null,null,3,6]

Output: false

Input and output use JSON-compatible values. For linked-list and tree questions, arrays represent the node structure as described above. Your code should implement solve(input).

Write your solutionImplement solve(input). Your draft is saved in this browser.

Compiler

How to solve Validate Binary Search Tree

Return true if the binary tree satisfies strict BST ordering. Input is a complete-index array with nulls. Propagate valid minimum and maximum bounds through the tree. The reference implementation illustrates this approach; check the example and edge cases.

Time and space complexity

O(n) time and O(h) recursion space.

Practise and improve

Choose JavaScript, TypeScript or Python, complete the starter code, then select Run Tests. Request a hint when you need guidance, or choose View solution and confirm if you would like to study the reference implementation.