【leetcode】【82】Remove Duplicates from Sorted List II

一、问题描述

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,

Given 

1->2->3->3->4->4->5

, return 

1->2->5

.

Given 

1->1->1->2->3

, return 

2->3

.

二、问题分析

首先head可能会被delete，所以最好额外添加一个头结点。剩下的无非就是链表的遍历问题。比较简单。

三、Java AC代码

public ListNode deleteDuplicates(ListNode head) {
if (head == null || head.next == null) {
return head;
}
ListNode dummy = new ListNode(0);
ListNode pre = dummy;
ListNode cur = head;
while (cur != null) {
if (cur.next != null && cur.val == cur.next.val) {
while (cur.next != null && cur.val == cur.next.val)
cur = cur.next;
} else {
pre.next = cur;
pre = pre.next;
}
cur = cur.next;
}
pre.next = null;
return dummy.next;
}