《剑指Offer》刷题笔记——面试题59-II. 队列的最大值

难度：中等

一、题目描述：

二、解题分析：

1、暴力法

import queue
class MaxQueue:

    def __init__(self):
        self.deque = queue.deque()

    def max_value(self) -> int:
        return max(self.deque) if self.deque else -1

    def push_back(self, value: int) -> None:
        self.deque.append(value)

    def pop_front(self) -> int:
        return self.deque.popleft() if self.deque else -1



# Your MaxQueue object will be instantiated and called as such:
# obj = MaxQueue()
# param_1 = obj.max_value()
# obj.push_back(value)
# param_3 = obj.pop_front()

2、单调双端队列

import queue
class MaxQueue:

    def __init__(self):
        self.deque = queue.deque()
        self.queue = queue.Queue()

    def max_value(self) -> int:
        return self.deque[0] if self.deque else -1


    def push_back(self, value: int) -> None:
        while self.deque and self.deque[-1] < value:
            self.deque.pop()
        self.deque.append(value)
        self.queue.put(value)

    def pop_front(self) -> int:
        if not self.deque:
            return -1
        ans = self.queue.get()
        if ans == self.deque[0]:
            self.deque.popleft()
        return ans


# Your MaxQueue object will be instantiated and called as such:
# obj = MaxQueue()
# param_1 = obj.max_value()
# obj.push_back(value)
# param_3 = obj.pop_front()