Given a Linked list of size N, the list is in alternating ascending and descending orders. Your task is to complete the function sort() that sorts the given linked list in non-decreasing order.

Input:
The function takes a single argument as input the reference pointer to the head of the linked list.
There are T test cases and for each test case the function will be called separately.

Output:
For each test case function should return reference pointer to the head of the new linked list.

User Task:
The task is to complete the function sort() which should sort the linked list in non-decreasing order

Note: Complete the task in constanst auxilliary space.

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(1)

Constraints:
1 <= T <= 100
1 <= N <= 100
0 <= A[] <= 10³

Example:
Input:
2
6
1 9 2 8 3 7
5
13 99 21 80 50

Output:
1 2 3 7 8 9
13 21 50 80 99

Explanation:
Testcase 1: After sorting the given linked list, the list will be as 1-> 2-> 3-> 7-> 8-> 9.
 

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