pythonキューの実装

Pythonを使用してキュー1を実現する.リストで

class Queue:
    def __init__(self):
        self.li = []
    def enqueue(self,x):
        self.li.append(x)
    def __str__(self):
        return str(self.li)
    def dequeue(self):
        self.li.pop(0)
if __name__ == '__main__':
    q = Queue()
    q.enqueue(1)
    q.enqueue(2)
    q.enqueue(3)
    q.enqueue(4)
    q.enqueue(5)
    q.dequeue()
    q.dequeue()
    print(q)

2.双方向チェーンで

class Node:
    def __init__(self,val):
        self.val = val
        self.next = None
        self.pre = None
class DoubleLink:
    def __init__(self):
        self.head = Node(None)
        self.tail = Node(None)
        self.head.next = self.tail
        self.tail.pre = self.head
class Queue1:
    def __init__(self):
        self.link = DoubleLink()
    def enqueue(self,x):
        node = Node(x)
        pre = self.link.tail.pre
        pre.next = node
        node.pre = pre
        node.next = self.link.tail
        self.link.tail.pre = node
    def dequeue(self):
        after = self.link.head.next.next
        self.link.head.next = after
        after.pre = self.link.head
    def __str__(self):
        l1 = []
        h = self.link.head.next
        t = self.link.tail
        while h is not t:
            l1.append(h.val)
            h = h.next
        return str(l1)
if __name__ == '__main__':
    q = Queue1()
    q.enqueue(1)
    q.enqueue(2)
    q.enqueue(3)
    q.enqueue(4)
    q.enqueue(5)
    q.dequeue()
    q.dequeue()
    print(q)