RemoveDuplicatesFromSortedListII

package leet;public class RemoveDuplicatesFromSortedListII {public ListNode deleteDuplicates(ListNode head) {if (head == null) {return null;}ListNode cur = head;ListNode pre = head;boolean isDelete = false;while (cur != null && cur.next != null) {if (cur.val == cur.next.val) {cur.next = cur.next.next;isDelete = true;} else {if (isDelete && head.val == cur.val) {head = cur.next;pre = head;cur = head;isDelete = false;continue;}if (isDelete) {pre.next = cur.next;} else {pre = cur;}cur = cur.next;isDelete = false;}}if (isDelete) {if (head.val == cur.val) {return null;} else {pre.next = null;}}return head;}}class ListNode {int val;ListNode next;ListNode(int x) {val = x;next = null;}}