LinkedList Circular

circular.js

/*
Given a linked list, return true if the list is circular, false if it is not.
*/

function circular(list) {
    let slow = list.getFirst();
    let fast = list.getFirst();
    
    for (let item of list) {
        if (slow.next && fast.next) {
            slow = slow.next;
            fast = fast.next.next;
            
            if (slow === fast) {
                return true;
            }
        }
    }
    
    return false;
}

function circular(list) {
    let slow = list.getFirst();
    let fast = list.getFirst();
    
    while (fast.next && fast.next.next) {
      slow = slow.next;
      fast = fast.next.next;
      
      if (slow === fast) {
        return true;
      }
    }
    
    return false;
}