Challenge 6: Detect Loop in a Linked List

Problem statement

By definition, a loop is formed when a node in your linked list points to a previously traversed node.

You must implement the DetectLoop() function, which will take a linked list as input, and deduce whether or not a loop is present.

Input

A doubly linked list is the input.

Output

It returns True if the given linked list contains a loop. Otherwise, it returns False.

Sample input

Linkedlist = 7->14->21->7 // Both '7's are the same node. Not duplicates.

Sample output

True