public ListNode FindKthToTail(ListNode head,int k) { if(head == null) return null; ListNode p = head; ListNode q = head; int m = k; while(k != 1){ if(p.next!=null){ p = p.next; k--; }else{ return null; } } while(p.next != null){ p = p.next; q = q.next; } return q; }