LinkedList Midpoint

midpoint.js

/*
Return the 'middle' node of a linked list.
  - If the list has an even number of elements return the node at the end of the first half of the list.
  - Do not use a counter variable
  - Do not retrieve the size of the list
  - Only iterate through the list one time
*/

function midpoint(list) {
  let slow = list.getFirst();
  let fast = list.getFirst();
  
  while (fast.next && fast.next.next) {
    slow = slow.next;
    fast = fast.next.next;
  }
  
  return slow;
}