public ListNode setTail(ListNode newTail) {
ListNode last = this;
while (last.next != null) last = last.next;
last.next = newTail;
return this;
}
public ListNode reverse() {
ListNode prev = null;
ListNode curr = this;
while (curr != null) {
ListNode tmp = curr.next;
curr.next = prev;
prev = curr;
curr = tmp;
}
return prev;
}