Binary Tree Cameras Problem Statement

Given a binary tree where each node can carry a camera that monitors its parent, itself, and its immediate children, determine the minimum number of cameras needed to monitor all the nodes.

Input:

The first line contains an integer 'T', representing the number of test cases. Each test case is specified as a single line containing elements in level order form, with node values separated by a single space. A -1 represents a null node.

Output:

An integer for each test case, representing the minimum number of cameras needed to monitor all nodes of the tree.

Example:

Input:

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

Output:

2

Constraints:

• 1 ≤ T ≤ 5
• 1 ≤ DATA ≤ 105 and DATA ≠ -1
• Time limit: 1 sec

Note:

Focus on implementing the function required. Input/output handling is already managed.