splitList(L):
|  Input  non-empty linked list L
|  Output L split into two halves
|
|  // use slow and fast pointer to traverse L
|  slow=head(L), fast=head(L).next
|  while fast≠NULL ∧ fast.next≠NULL do
|     slow=slow.next, fast=fast.next.next  // advance pointers
|  end while
|  cut L between slow and slow.next