使用数组实现一个简单的队列

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

    def enqueue(self, item):
        if self.isFull():
            print("Queue is full.")
        else:
            if self.isEmpty():
                self.head = 0
            self.tail += 1
            self.queue[self.tail] = item

    def dequeue(self):
        if self.isEmpty():
            print("Queue is empty.")
        else:
            item = self.queue[self.head]
            self.queue[self.head] = None
            self.head += 1
            if self.head > self.tail:
                self.head = -1
                self.tail = -1
            return item

    def isEmpty(self):
        return self.head == -1 and self.tail == -1

    def isFull(self):
        return self.tail == self.size - 1


# 示例代码的使用
queue = Queue(5)
queue.enqueue(1)
queue.enqueue(2)
queue.enqueue(3)
print(queue.dequeue())  # 输出：1
print(queue.dequeue())  # 输出：2
print(queue.isEmpty())  # 输出：False
print(queue.isFull())   # 输出：False