java删除单链表中的重复节点

package offer;
/*
* 1、删除单链表中的重复节点
* 输入 ： 2, 3, 3, 5, 7, 8, 8, 8, 9, 9, 10
* 输出 ： 2 5 7 10
*
* 2、单链表中重复节点只保留一个
* 输入 ： 2, 3, 3, 5, 7, 8, 8, 8, 9, 9, 10
* 输出 ： 2 3 5 7 8 9 10
*
*
*/
public class DeleteReNode {

//删除单链表中的重复节点
public static ListNode deleteDuplication(ListNode pHead)
{
    if(pHead==null)
        return pHead;
    ListNode first = new ListNode(0);
    first.next = pHead;
    ListNode p = pHead;
    ListNode pre = first;
    while (p != null && p.next != null){
        if(p.val == p.next.val) {
           int val = p.val;

            //只需把下面的while改为注释的while，即可由情形1得到2
           /*
             while(p.next != null && p.next.val == val) {
                p.next = p.next.next;
            }
            */

            while(p != null && p.val == val) {
                p = p.next;
            }

            pre.next = p;
        }else {
            pre= p;
            p = p.next;
        }
    }
    while(first.next != null) {
        System.out.print(first.next.val + " ");
        first = first.next;
    }
    return first.next;
}

public static void main(String[] args) {
    //-构造单链表start----
    int[] num = { 2, 3, 3, 5, 7, 8, 8, 8, 9, 9, 10 }; 
    ListNode head = new ListNode(num[0]);
    ListNode pre = head;
    for (int i = 1; i < num.length; i++) {
        ListNode node = new ListNode(num[i]);
        pre.next = node;
        pre = node;
    }
    //-构造单链表end-----

    deleteDuplication(head);
}

}

class ListNode {
int val;
ListNode next = null;
ListNode(int val) {
this.val = val;
}
}