reverse linked list in java to get both head and tail
/*
public class ListNode {
public int val;
public ListNode next;
public ListNode(int x) { val = x; next = null; }
}
*/
public static ListNode[] reverse_linked_list(ListNode head) {
ListNode prev = null;
ListNode current = head;
ListNode next;
ListNode tail = head;
while (current != null) {
next = current.next;
current.next = prev;
prev = current;
current = next;
}
head = prev;
ListNode[] result = {head, tail};
return result;
}