Linked List Cycle Detection | JS Solution

HackerRank detailed problem description can be found here.

Problem

Determine if a provided singly linked list has a cycle in it, meaning if any node is visited more than once while traversing the list.

Inputs & Outputs

/*
param {Node} head
return {number} 1 or 0
*/

Code

function hasCycle(head) {
  if (!head) {
    return 0;
  }

  let fast = head;
  let slow = head;

  while (fast) {
    fast = fast.next;
    if (fast) {
      fast = fast.next;
      slow = slow.next;

      if (fast === slow) {
        return 1;
      }
    }
  }
  return 0;
}

Sources & Resources:

1. Cycle Detection Algorithm by HackerRank
2. Data Structures: Linked Lists by HackerRank