82. Remove Duplicates from Sorted List II
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
//剑指offer删除链表中重复的结点
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Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.
class Solution {
public ListNode deleteDuplicates(ListNode head) {
if (head == null)
return null;
ListNode dummy = new ListNode(0);
dummy.next = head;
ListNode pre = dummy;
ListNode cur = head;
while (cur != null) {
while (cur.next != null && cur.val == cur.next.val)
cur = cur.next; //遇到重复元素，cur就指向最后一个重复元素
if (pre.next == cur)
pre = pre.next;
else //此时遇到了重复元素，原本的cur改变了，如2->3->3->4，此时pre是2，cur指到了第二个3，则2直接指向4，相当于删去了重复元素
pre.next = cur.next;
cur = cur.next;
}
return dummy.next;
}
}
