Challenge: Detect Loop in a Linked List - Hashing

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 detect_loop() function which will take a linked list as input and deduce whether or not a loop is present.

You have already seen this in Challenge: Detect Loop in a Linked List. Here you would use HashTables for a more efficient solution.

Input

A singly linked list.

Output

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