public class MyLeetCode82 {

	public static class ListNode {

		int val;

		ListNode next;

		ListNode(int x) {

			val = x;

		}

	}

	public static ListNode deleteDuplicates(ListNode head) {

		if (head == null || head.next == null) {

			return head;

		}

		ListNode fakeNode = new ListNode(-1);

		ListNode root = fakeNode;

		ListNode prev = head;

		ListNode cur = head;

		while (cur != null && cur.next != null) {

			while (cur.next != null && cur.next.val == prev.val) {

				cur = cur.next;

			}

			if (cur == prev) {

				// 指针没动过,代表当前第一个就是不重复的

				root.next = prev;

				root = root.next;

			}

			prev = cur.next;

			cur = cur.next;

		}

		if (prev == cur && prev != null) {

			root.next = cur;

			root = root.next;

		}

		root.next = null;

		return fakeNode.next;

	}

}