GPT答：

7i24.cn

下面是一个使用单链表实现有序集合的Python代码示例：

```python
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class Set:
    def __init__(self):
        self.head = None

    def add(self, item):
        if not self.contains(item):
            new_node = Node(item)
            if not self.head or item < self.head.data:
                new_node.next = self.head
                self.head = new_node
            else:
                current = self.head
                while current.next and current.next.data < item:
                    current = current.next
                new_node.next = current.next
                current.next = new_node

    def remove(self, item):
        if not se