Postorder Successor Problem Statement

You are provided with a binary tree consisting of 'N' distinct nodes and an integer 'M'. Your task is to find and return the postorder successor of 'M'.

Note:

The postorder successor of a node 'M' is the subsequent element to 'M' in the sequence resulting from postorder tree traversal.

If in postorder traversal the sequence is 3 5 4 7, then clearly, the postorder successor of 5 is 4. If there is no postorder successor of 'M', return '-1'.

Input:

The first line consists of an integer 'T' representing the number of test cases.

Then, each test case starts with a line containing the elements of the tree presented in level order format, with values of nodes separated by a space. In case of a NULL node, '-1' is used.
The second line of each test case provides 'M', the node whose postorder successor must be discovered.

Example:
1
3 8
5 2 7 -1
-1 -1 -1 -1 -1 -1

Output:

Output an integer representing the post-order successor of node 'M' in the binary tree.
Each test case result should be printed on a new line.

Example:

Input:

1 3 8 5 2 7 -1 -1 -1 -1 -1 -1 1

Output:

3

Constraints:

• 1 <= 'T' <= 5
• 1 <= 'N' <= 3000
• 1 <= 'M' <= 3000
• 1 <= nodeVal <= 10⁹
• Time Limit: 1 sec

Note:

You need not print anything; handle the implementation as specified in the problem.