Leetcode 刷题 (11) 队列：设计循环队列

Maha ·

更新时间:2024-11-15

· 551 次阅读

题目： 622. 设计循环队列

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难度：中等
题目分析：看下面代码实现。参考的是裘宗燕的《数据结构与算法：Python语言描述》。此处不建议使用python内置的list的append, pop操作，使用了就违背设计循环队列的初衷：消除代价为O(n)的出队操作。

解法：

class MyCircularQueue:
    def __init__(self, k: int):
        """
        Initialize your data structure here. Set the size of the queue to be k.
        """
        # 入队在位置 head + num % len; 满的话，num == len; 空的话，num == 0
        self.head = 0
        self.num = 0
        self.queue = [0]*k
        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.len == self.num: # 满了
            return False
        self.queue[(self.head + self.num) % self.len] = value
        self.num += 1
        return True
    def deQueue(self) -> bool:
        """
        Delete an element from the circular queue. Return true if the operation is successful.
        """
        if self.num == 0:
            return False
        self.head = (self.head + 1) % self.len
        self.num -= 1
        return True
    def Front(self) -> int:
        """
        Get the front item from the queue.
        """
        if self.num == 0:
            return -1
        return self.queue[self.head]
    def Rear(self) -> int:
        """
        Get the last item from the queue.
        """
        if self.num == 0:
            return -1
        return self.queue[(self.head + self.num - 1) % self.len]
    def isEmpty(self) -> bool:
        """
        Checks whether the circular queue is empty or not.
        """
        return self.num == 0
    def isFull(self) -> bool:
        """
        Checks whether the circular queue is full or not.
        """
        return self.num == self.len
# 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()

运行结果：

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