# 定义一个节点类Node
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

# 定义链表类LinkedList
class LinkedList:
    def __init__(self):
        self.head = None
        self.tail = None
    
    # 定义链表的append方法（向链表尾部追加节点）
    def append(self, value):
        node = Node(value)
        if self.head is None:
            self.head = node
            self.tail = node
        else:
            self.tail.next = node
            self.tail = node
    
    # 定义链表的iter方法（迭代出链表的所有节点）
    def iter(self):
        cur = self.head
        if cur is None:
            print('Empty linkedList...')
            return
        while cur:
            yield cur.data
            cur = cur.next

    # 定义链表的insert方法（在指定索引处插入节点）
    def insert(self, idx, value):
        cur_idx = 0
        cur = self.head
        node = Node(value)
        if cur is None:
            if idx <= 0:
                self.head = node
                self.tail = node
                return
        if idx < 0:
            print('insert idx too small')
            return
        while cur:
            if idx - 1 > cur_idx:
                cur = cur.next
                cur_idx += 1
            else:
                break
        else:
            print('inserted idx too lager')
            return
        node.next = cur.next
        cur.next = node
        if node.next is None:
            self.tail = node

    # 定义链表的remove方法（删除指定索引处的节点）
    def remove(self, idx):
        cur_idx = 0
        cur = self.head
        if cur is None:
            raise Exception('Empty link list, can not remove elements.')
        if idx < 0:
            raise Exception('removed idx is too small...')
        if idx == 0:
            if cur.next is None:
                self.head = None
                self.tail = None
            else:
                self.head = cur.next
            return
        while cur:
            if idx - 1 > cur_idx:
                cur_idx += 1
                cur = cur.next
            else:
                break
        else:
            raise Exception('removed idx too lager')
        if cur.next is None:
            raise Exception('removed idx too lager')
        cur.next = cur.next.next
        if cur.next is None:
            self.tail = cur

# 测试调用
if __name__ == '__main__':

    link_list = LinkedList()

    for i in range(10):
        link_list.append(i)
    #
    # print(link_list.insert(0, 10))
    # # print('------')
    # print(link_list.insert(1, 11))
    # print('------')
    #
    # link_list.insert(-1, 20)
    link_list.remove(10)

    for node in link_list.iter():
        print(node)
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