[LintCode] #113 Remove Duplicates from Sorted List II

/**
 * Definition for ListNode
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    /**
     * @param ListNode head is the head of the linked list
     * @return: ListNode head of the linked list
     */
    public static ListNode deleteDuplicates(ListNode head) {
        // write your code here
        ListNode dummy = new ListNode(-1);
        dummy.next = head;
        ListNode pre = dummy;
        ListNode cur = head;
        while (cur != null) {
            if (cur.next != null && cur.val == cur.next.val) {
                int val = cur.val;
                while (cur != null && cur.val == val) {
                    pre.next = cur.next;
                    cur = cur.next;
                }
            } else {
                pre = cur;
                cur = cur.next;
            }
        }
        return dummy.next;
    }
}