Deepest Leaves Sum Problem Statement

Given a binary tree of integers, your task is to calculate the sum of all the leaf nodes present at the deepest level of this binary tree. If there are no such nodes, output 0.

Input:

The first line contains an integer 'T' denoting the number of test cases. 
Each test case includes one line of elements in level order form, with node values separated by a single space. A null node is represented by -1.

Output:

For each test case, output the sum of all leaf nodes at the deepest level, printed on a new line.

Example:

Input:

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

Output:

7

Explanation:

The binary tree represented by the input has depth levels as depicted in a given image, with the deepest leaves being [7], thus the sum is 7.

Constraints:

• 1 ≤ T ≤ 10²
• 0 ≤ N ≤ 3000
• The sum is guaranteed to fit within a 32-bit integer.
• Time limit: 1 second.

Note:

You do not need to handle printing the output in your submission. Focus on implementing the function to solve the problem.