Finding loop in a singly linked-list

Question

How can I detect that whether a singly linked-list has loop or not?? If it has loop then how to find the point of origination of the loop i.e. the node from which the loop

Answer 1

A quite different method:- Reverse the linked list. While reversing if you reach the head again then there is a loop in the list, if you get NULL then there is no loop. The total time complexity is O(n)