5902.py

from collections import deque

class MaxQueue:

    def __init__(self):
        self.que = deque()
        self.sort_que = deque()

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

    def push_back(self, value: int) -> None:
        self.que.append(value)
        # sort_que: non-increasing 非递增
        while self.sort_que and self.sort_que[-1] < value:
            self.sort_que.pop()
        self.sort_que.append(value)

    def pop_front(self) -> int:
        if not self.que:
            return -1
        res = self.que.popleft()  # popleft(): O(1), pop(i): O(n)
        if res == self.sort_que[0]:
            self.sort_que.popleft()
        return res

# 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()