2.1

removeDupinLinkedList.java

/**
 * Created by Readman on 6/23/14.
 */
public class removeDupinLinkedList {
    public static void removeDupinLinkedList(ListNode head) {
        if (head == null || head.next == null)
            return;
        ListNode slow = head;
        ListNode fast = head.next;
        ListNode pre = head;
        while (slow != null) {
            while (fast != null) {
                if (slow.val == fast.val) {
                     pre.next = fast.next;
                }
                else {
                    pre = pre.next;
                }
                fast = fast.next;
            }
            pre = slow.next;
            slow = slow.next;
            if (slow != null)
                fast = slow.next;
        }
    }
    public static void main(String[] args) {
        ListNode head = new ListNode(1);
        head.next = new ListNode(3);
        head.next.next = new ListNode(3);
        head.next.next.next = new ListNode(2);
        head.next.next.next.next= new ListNode(2);
        head.next.next.next.next.next = new ListNode(2);
        head.next.next.next.next.next.next = new ListNode(2);
        removeDupinLinkedList(head);
        while (head != null) {
            System.out.print(head.val + " ");
            head = head.next;
        }
    }
}

main里的代码好丑啊