Triplet Count in a Sorted Doubly Linked List Problem

Count the number of triplets in a sorted doubly linked list such that their sum equals a given integer 'X'. The list is composed of distinct node values.

Explanation:

A sorted doubly linked list contains nodes with data and pointers for both the previous and next nodes. This ensures you can navigate forwards and backwards through the list.

Input:

The first line of the input contains an integer 'T', representing the number of test cases.
The next '2*T' lines represent the 'T' test cases.
For each test case:
- The first line contains space-separated integers representing the node values of the linked list. Each line ends with -1, indicating the end of the list.
- The second line has a single integer 'X', the target value for the triplet sum.

Output:

For each test case, output a single integer on a new line, representing the count of triplets that sum up to 'X'.

Example:

Input:
1
1 2 3 4 -1
9

Output:
1

Explanation:

For the given example, the list is 1<->2<->3<->4 NULL, and 'X' is 9. The only possible triplet with sum 9 is (2,3,4).

Constraints:

• 1 ≤ 'T' ≤ 10
• 3 ≤ 'N' ≤ 100
• 1 ≤ 'X' ≤ 10⁸
• 1 ≤ 'V' ≤ 10⁸, where 'V' is any linked list element
• Time limit: 1 sec

Note:

- If no such triplets exist, return zero.
- At least three elements will always be present in the linked list.
- You do not need to handle input or output; implement the function logic only.