Size of Largest BST in a Binary Tree

Given a binary tree with 'N' nodes, determine the size of the largest subtree that is also a Binary Search Tree (BST).

Explanation:

A Binary Search Tree (BST) is defined as follows:

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

Input:

The first line contains an integer 'T', representing the number of test cases. Each test case follows: A single line with space-separated values representing the binary tree in level order. Use -1 for null nodes.

Output:

For each test case, return an integer that indicates the size of the largest BST subtree within the binary tree.

Example:

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

Output:
3

Explanation: In the given tree, the largest subtree that is also a BST has 3 nodes.

Constraints:

• 1 <= T <= 100
• 1 <= N <= 5000
• 1 <= data <= 10⁵ and data != -1

Note: You do not need to print anything; simply implement the function to return the result.