"""
请定义一个队列并实现函数 max_value 得到队列里的最大值，要求函数max_value、push_back 和 pop_front 的均摊时间复杂度都是O(1)。

若队列为空，pop_front 和 max_value 需要返回 -1

示例 1：

输入: 
["MaxQueue","push_back","push_back","max_value","pop_front","max_value"]
[[],[1],[2],[],[],[]]
输出: [null,null,null,2,1,2]
示例 2：

输入: 
["MaxQueue","pop_front","max_value"]
[[],[],[]]
输出: [null,-1,-1]
 

限制：

1 <= push_back,pop_front,max_value的总操作数 <= 10000
1 <= value <= 10^5

来源：剑指offer
链接：https://leetcode-cn.com/problems/dui-lie-de-zui-da-zhi-lcof

"""

class MaxQueue:

    def __init__(self):
        self.queue = []
        


    def max_value(self) -> int:
        if not self.queue:
            return -1
        return max(self.queue)

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


    def pop_front(self) -> int:
        if not self.queue:
            return -1
        return self.queue.pop(0)


# 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()