82. Remove Duplicates from Sorted List II

SLinkedList slist = new SLinkedList();
slist.AppendRange(new[] { 6, 1, 1, 2, 3, 3, 3, 4, 5, 5 });
Console.WriteLine("Before: " + slist.Print());
var rslt = slist.DeleteDuplicates();
Console.WriteLine(" After: " + rslt.Print());

/// 

/// 删除链表中重复的结点，只要是有重复过的结点，全部删除。
/// 
/// 
/// 
/// 
public static SLinkedList DeleteDuplicates(this SLinkedList source) where T : IComparable
{
    if (source.IsEmpty())
    {
        return null;
    }
    if (source.Head == null || source.Head.Next == null)
    {
        return source;
    }
    var tmp = new SLinkedList(source);
    var head = DeleteDuplicates(tmp.Head);
    tmp.Clear();
    return new SLinkedList(head);
}

private static SLinkedListNode DeleteDuplicates(SLinkedListNode head) where T : IComparable
{
    if (head == null)
    {
        return null;
    }
    if (head.Next != null && head.IsEqualTo(head.Next))
    {
        while (head.Next != null && head.IsEqualTo(head.Next))
        {
            head = head.Next;
        }
        return DeleteDuplicates(head.Next);
    }
    head.Next = DeleteDuplicates(head.Next);
    return head;
}