You are given the head of a linked list which probably contains a loop. If the list contains a loop, you need to find the last node of the list which points to one of its previous nodes to create a loop and make it point to NULL, thereby removing the loop

Problem Note:

• It's possible that the linked list does not contain a loop
• Do not use extra space

Example 1

Input:   1 -> 2 -> 3 -> 4 -> 5
                   |         |
                   |         |    
                   - - - - - -
Output:  1 -> 2 -> 3 -> 4 -> 5
Explanation: The node 5 at the end of loop points to 3 and creates a loop. We make it point to NULL and remove the loop.

Example 2

Input: 2 -> 20 -> 6 -> 19 -> 13 -> 4
Output: 2 -> 20 -> 6 -> 19 -> 13 -> 4
Explanation: No loop present.