Step Back From the Tail

Directions

Given a linked list, return the element n spaces from the last node in the list.
Do not call the 'size' method of the linked list. Assume that n will always be less than the length of the list.

Use LinkedList file.

Examples:

const list = new List();
list.insertLast('a');
list.insertLast('b');
list.insertLast('c');
list.insertLast('d');
fromLast(list, 2).data // 'b'

Solutions

• Solution #1

    function fromLast(list, n) {
      let slow = list.getFirst();
      let fast = list.getFirst();
    
      while (n > 0) {
        fast = fast.next;
        n--;
      }
    
      while (fast.next) {
        slow = slow.next;
        fast = fast.next;
      }
    
      return slow;
    }