Reverse Doubly Linked List in Groups Problem

You are provided with a Doubly Linked List consisting of integers and a positive integer 'K', which represents the size of the group. Your task is to modify the linked list by reversing every group of 'K' nodes in the list.

A doubly linked list is bidirectional, meaning it can be traversed both forward and backward.

Example:

Input:

Linked list: 8 9 10 11 12
K: 3

Output:

10 9 8 12 11

Explanation:

Reverse the first K (3) nodes. The remaining nodes (11 and 12) are less than K, so reverse them as well.

Input:

The first line contains an integer T, indicating the number of test cases.
The first line of each test case provides the elements of the doubly linked list, separated by a space and ending with -1, which is not a list element.
The second line specifies the positive integer 'K'.

Output:

For each test case, output the modified linked list. The elements of the modified list should be single-space separated and end with -1.

Constraints:

• 1 <= T <= 10
• 1 <= N <= 5 * 104
• 1 <= K <= 105
• -103 <= data <= 103 (and data != -1)

Note:

You don't have to print anything. Implement the function as directed.