编写程序实现循环队列的初始化、判断队列空否、入队列和出队列等

操作。

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

    def is_empty(self):
        return self.front == -1

    def is_full(self):
        if self.front == 0 and self.rear == self.capacity - 1:
            return True
        if self.front == self.rear + 1:
            return True
        return False

    def enqueue(self, data):
        if self.is_full():
            print("Queue is full.")
            return
        if self.front == -1:
            self.front = 0
        self.rear = (self.rear + 1) % self.capacity
        self.queue[self.rear] = data

    def dequeue(self):
        if self.is_empty():
            print("Queue is empty.")
            return
        data = self.queue[self.front]
        self.queue[self.front] = None
        if self.front == self.rear:
            self.front = -1
            self.rear = -1
        else:
            self.front = (self.front + 1) % self.capacity
        return data

使用示例：

queue = CircularQueue(5)

queue.enqueue(1)
queue.enqueue(2)
queue.enqueue(3)
queue.enqueue(4)
queue.enqueue(5)
queue.enqueue(6)  # Queue is full.

print(queue.dequeue())  # 1
print(queue.dequeue())  # 2

queue.enqueue(6)
queue.enqueue(7)

print(queue.dequeue())  # 3
print(queue.dequeue())  # 4
print(queue.dequeue())  # 5
print(queue.dequeue())  # 6
print(queue.dequeue())  # 7

queue.dequeue()  # Queue is empty.