(1)采用链式存储实现栈的初始化、入栈、出栈操作。(2)采用顺序存储实现栈的初始化、入栈、出栈操作。 (3)采用链式存储实现队列的初始化、入队、出队操作。 (4)采用顺序存储实现循环队列的初始化、入队、出队操作。(5)在主函数中设计一个简单的菜单，分别测试上述算法。

1. 链式存储实现栈的初始化、入栈、出栈操作

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

class Stack:
    def __init__(self):
        self.top = None

    def is_empty(self):
        return self.top is None

    def push(self, data):
        node = Node(data)
        node.next = self.top
        self.top = node

    def pop(self):
        if self.is_empty():
            return None
        data = self.top.data
        self.top = self.top.next
        return data

2. 顺序存储实现栈的初始化、入栈、出栈操作

class Stack:
    def __init__(self):
        self.data = []

    def is_empty(self):
        return len(self.data) == 0

    def push(self, data):
        self.data.append(data)

    def pop(self):
        if self.is_empty():
            return None
        return self.data.pop()

3. 链式存储实现队列的初始化、入队、出队操作

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

class Queue:
    def __init__(self):
        self.front = None
        self.rear = None

    def is_empty(self):
        return self.front is None

    def enqueue(self, data):
        node = Node(data)
        if self.is_empty():
            self.front = node
            self.rear = node
        else:
            self.rear.next = node
            self.rear = node

    def dequeue(self):
        if self.is_empty():
            return None
        data = self.front.data
        self.front = self.front.next
        if self.front is None:
            self.rear = None
        return data

4. 顺序存储实现循环队列的初始化、入队、出队操作

class Queue:
    def __init__(self, size):
        self.data = [None] * size
        self.front = 0
        self.rear = 0
        self.size = size

    def is_empty(self):
        return self.front == self.rear

    def is_full(self):
        return (self.rear + 1) % self.size == self.front

    def enqueue(self, data):
        if self.is_full():
            return False
        self.data[self.rear] = data
        self.rear = (self.rear + 1) % self.size
        return True

    def dequeue(self):
        if self.is_empty():
            return None
        data = self.data[self.front]
        self.front = (self.front + 1) % self.size
        return data

5. 主函数中的菜单

def main():
    stack = Stack()
    queue = Queue()

    while True:
        print("1. Push to stack")
        print("2. Pop from stack")
        print("3. Enqueue to queue")
        print("4. Dequeue from queue")
        print("0. Exit")

        choice = int(input("Enter your choice: "))

        if choice == 1:
            data = input("Enter data: ")
            stack.push(data)
        elif choice == 2:
            data = stack.pop()
            if data is None:
                print("Stack is empty")
            else:
                print("Popped data:", data)
        elif choice == 3:
            data = input("Enter data: ")
            queue.enqueue(data)
        elif choice == 4:
            data = queue.dequeue()
            if data is None:
                print("Queue is empty")
            else:
                print("Dequeued data:", data)
        elif choice == 0:
            break
        else:
            print("Invalid choice")