Boundary Sum Problem Statement

Given a Binary Tree with 'N' nodes, compute and return the sum of all its boundary nodes. The boundary nodes include the root node, leftmost external nodes, rightmost external nodes, and all the leaves of the tree.

Explanation:

In the provided binary tree example, we have the following boundary nodes:

• Root: 2
• Leftmost: 35
• Rightmost: 10
• Leaf nodes: 2, 3, 5, 2

The total sum of these nodes would be 59.

Input:

The first line contains an integer 'T' denoting the number of test cases. Each test case consists of a single line containing the elements of the tree in level order, separated by a space. Use -1 for nonexistent children.

Output:

For each test case, output a single integer representing the sum of the boundary nodes. Each output should be on a new line.

Example:

Tree nodes in level order:

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

For this tree, the boundary nodes are formed as follows:

• Root: 1
• Leftmost: 2
• Rightmost: 3
• Leaf nodes: 4, 5, 6, 7

Boundary sum would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28.

Constraints:

• 1 <= T <= 100
• 1 <= N <= 1000
• -10⁶ <= node.data <= 10⁶
• Each node data value is bounded within the range from -10⁶ to 10⁶.
• Time Limit: 1 second

Note:

You do not need to print anything explicitly. Just implement the function as required.