Midpoint of Linked List

Directions

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, and only iterate
through the list one time.


Use LinkedList file.

Examples:

const l = new LinkedList();
l.insertLast('a')
l.insertLast('b')
l.insertLast('c')
midpoint(l); // returns { data: 'b' }

Solutions

• Solution

    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;
    }