Leetcode: Remove Duplicates from Sorted List II 解题报告

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.

For example,
Given

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

, return

1->2->5

.
Given

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

, return

2->3

.

/**
* Definition for singly-linked list.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) {
*         val = x;
*         next = null;
*     }
* }
*/
public 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 = pre.next;

while (cur != null && cur.next != null) {
if (cur.val == cur.next.val) {
while (cur != null && cur.val == pre.next.val) {
cur = cur.next;
}

// delete all the duplication.
pre.next = cur;
} else {
cur = cur.next;
pre = pre.next;
}
}

return dummy.next;
}
}

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