Validate BST Problem Statement

Given a binary tree with N nodes, determine whether the tree is a Binary Search Tree (BST). If it is a BST, return true; otherwise, return false.

A binary search tree (BST) is a binary tree with the following properties:

• The left subtree of a node contains only nodes with data less than the node's data.
• The right subtree of a node contains only nodes with data greater than the node's data.
• Both the left and right subtrees must also be binary search trees.

Input:

The first line contains an integer t, indicating the number of test cases. Each test case consists of a single line containing the elements of the tree in level order form separated by a single space. If any node does not have a left or right child, use -1 in its place.

Output:

For each test case, return true if the binary tree is a BST, otherwise return false. Output for each test case should be in a separate line.

Example:

Input:

1
1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1

Output:

true

Explanation:

The given input corresponds to a tree where each node satisfies the properties of a BST.

Constraints:

• 1 <= T <= 100
• 1 <= N <= 1000
• -106 <= data <= 106

Where N is the number of nodes in the tree, T represents the number of test cases, and data denotes the data contained in each node of the binary tree.

Note:

You do not need to print anything explicitly. The implementation handles printing the result for each test case.