剑指 Offer 59 - II. 队列的最大值

剑指 Offer 59 - II. 队列的最大值

地址:剑指 Offer 59 - II. 队列的最大值

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


type MaxQueue struct {
    queue   []int
    max     []int
}


func Constructor() MaxQueue {
    return MaxQueue{
        queue : make([]int, 0),
        max: make([]int, 0),
    }
}


func (this *MaxQueue) Max_value() int {
    if len(this.queue) == 0 {return -1}
    return this.max[0]
}


func (this *MaxQueue) Push_back(value int)  {
    this.queue = append(this.queue, value)
    for len(this.max) > 0 && value > this.max[len(this.max)-1] {
        this.max = this.max[:len(this.max)-1]
    }
    this.max = append(this.max, value)
}


func (this *MaxQueue) Pop_front() int {
    if len(this.queue) == 0 {return -1}
    tmp := this.queue[0]
    if this.max[0] == tmp {
        this.max = this.max[1:]
    }
    this.queue = this.queue[1:]
    return tmp
}


/**
 * Your MaxQueue object will be instantiated and called as such:
 * obj := Constructor();
 * param_1 := obj.Max_value();
 * obj.Push_back(value);
 * param_3 := obj.Pop_front();
 */
posted @ 2021-01-25 13:34  ganshuoos  阅读(58)  评论(0编辑  收藏  举报