入队和出队排队时间复杂度的有效实现

class Node:
    def __init__(self, value):
        self.value = value
        self.next = None

class Queue:
    def __init__(self):
        self.head = None
        self.tail = None

    def enqueue(self, value):
        new_node = Node(value)
        if not self.tail:
            self.head = self.tail = new_node
        else:
            self.tail.next = new_node
            self.tail = new_node

    def dequeue(self):
        if not self.head:
            return None
        value = self.head.value
        self.head = self.head.next
        if not self.head:
            self.tail = None
        return value

class CircularQueue:
    def __init__(self, capacity):
        self.capacity = capacity
        self.queue = [None] * capacity
        self.head = self.tail = -1

    def enqueue(self, value):
        if (self.tail + 1) % self.capacity == self.head:
            return False  # Queue is full
        if self.head == -1:
            self.head = 0
        self.tail = (self.tail + 1) % self.capacity
        self.queue[self.tail] = value
        return True

    def dequeue(self):
        if self.head == -1:
            return None  # Queue is empty
        value = self.queue[self.head]
        if self.head == self.tail:
            self.head = self.tail = -1
        else:
            self.head = (self.head + 1) % self.capacity
        return value