Counting Nodes in a Complete Binary Tree - Problem Statement

Given the root of a complete binary tree, calculate the total number of nodes in this tree.

A complete binary tree is defined as a binary tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possible in the last level.

Example:

Input:

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

Output:

7

Explanation:

In the given complete binary tree, the total number of nodes is 7. The tree structure with level order:
- Level 1: root node 1
- Level 2: left child of 1 is 2, right child is 3
- Level 3: left child of 2 is 4, right child is null (-1), left child of 3 is 5, right child is 6
- Level 4: left child of 4 is null (-1), right is 7; other nodes in this level are null due to -1

Constraints:

• 1 <= T <= 10
• 0 <= Number of nodes in tree <= 10⁵
• 1 <= Node's value <= 5 × 10⁵

Note:

The input format is provided to demonstrate how the level order sequence can be represented with null nodes depicted as -1, combined into a single line for each test case.