Extract middle element from a single linked list [closed]

Question

I have a question:

Find the middle element from a single linked list.

I need to know the way/method of this problem.

Answer 1

You can use two pointers to iterate through the list - one which iterates twice as fast as the other. When the fast pointer reaches the end of the list then the slow pointer will be pointing at the mid-point.

Algorithm:

init slow_pointer = head
init fast_pointer = head
repeat
   fast_pointer = fast_pointer->next;
   if fast_pointer == NULL
      break;
   fast_pointer = fast_pointer->next;
   if fast_pointer == NULL
      break;
   slow_pointer = slow_pointer->next;
until false
// slow_pointer now points at the middle node