设计循环队列

 你的实现应该支持如下操作：

• MyCircularQueue(k): 构造器，设置队列长度为 k 。
• Front: 从队首获取元素。如果队列为空，返回 -1 。
• Rear: 获取队尾元素。如果队列为空，返回 -1 。
• enQueue(value): 向循环队列插入一个元素。如果成功插入则返回真。
• deQueue(): 从循环队列中删除一个元素。如果成功删除则返回真。
• isEmpty(): 检查循环队列是否为空。
• isFull(): 检查循环队列是否已满。

力扣初始化用-1，指针是一直递增的，通过head % len来确定现位置，这样 (tail - head) % len == 0就可以确定是否已满

class MyCircularQueue:

    def __init__(self, k: int):
        """
        Initialize your data structure here. Set the size of the queue to be k.
        """
        self.queue = [-1] * k
        self.head = 0
        self.tail = 0
        self.len = k
        

    def enQueue(self, value: int) -> bool:
        """
        Insert an element into the circular queue. Return true if the operation is successful.
        """
        if self.isFull():
            return False
        
        if self.isEmpty():
            self.queue[self.tail % self.len] = value
        else:
            self.tail += 1
            self.queue[self.tail % self.len] = value
        return True
        

    def deQueue(self) -> bool:
        """
        Delete an element from the circular queue. Return true if the operation is successful.
        """
        if self.isEmpty():
            return False
        else:
            self.queue[self.head % self.len] = -1
            if self.head + 1 > self.tail:
                pass
            else:
                self.head += 1
            return True

    def Front(self) -> int:
        """
        Get the front item from the queue.
        """
        return self.queue[self.head % self.len]
        

    def Rear(self) -> int:
        """
        Get the last item from the queue.
        """
        return self.queue[self.tail % self.len]
        

    def isEmpty(self) -> bool:
        """
        Checks whether the circular queue is empty or not.
        """
        if self.queue[self.head % self.len] == -1:
            return True
        return False

    def isFull(self) -> bool:
        """
        Checks whether the circular queue is full or not.
        """
        if (self.tail - self.head + 1) % self.len == 0:
            return True
        return False


# Your MyCircularQueue object will be instantiated and called as such:
# obj = MyCircularQueue(k)
# param_1 = obj.enQueue(value)
# param_2 = obj.deQueue()
# param_3 = obj.Front()
# param_4 = obj.Rear()
# param_5 = obj.isEmpty()
# param_6 = obj.isFull()