Convert a Binary Tree to a Sum Tree

Given a binary tree of integers, convert the binary tree into a sum tree where each node's value is replaced by the sum of the values of its left and right subtrees in the original tree. The value of leaf nodes should be set to zero.

Input:

1. An integer T representing the number of test cases.
2. For each test case, a line with level order traversal of the binary tree with node values separated by a space. Use -1 to denote null nodes. -1 is not included in actual tree node values.

Output:

For each test case, produce a line of level order traversal of the sum tree with node values separated by spaces, using -1 to represent null nodes.

Example:

Input:

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

Output:

[output would depend on internal calculations of the sum tree] 

Constraints:

• 1 <= T <= 100
• 1 <= N <= 3000
• -10⁴ <= val <= 10⁴ and val != -1

Note:

The binary tree is passed in level order format, using -1 for null nodes. Actual node values will never be -1. Implement the function and return the result, printing is handled separately.