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 <= 100001 <= value <= 10^5
利用一个辅助队列按单调顺序存储当前队列的最大值。
class MaxQueue:
def __init__(self):
self.p = deque()
self.q = deque()
def max_value(self) -> int:
return -1 if not self.q else self.q[0]
def push_back(self, value: int) -> None:
while self.q and self.q[-1] < value:
self.q.pop()
self.p.append(value)
self.q.append(value)
def pop_front(self) -> int:
if not self.p:
return -1
res = self.p.popleft()
if self.q[0] == res:
self.q.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()class MaxQueue {
private Deque<Integer> p;
private Deque<Integer> q;
public MaxQueue() {
p = new ArrayDeque<>();
q = new ArrayDeque<>();
}
public int max_value() {
return q.isEmpty() ? -1 : q.peekFirst();
}
public void push_back(int value) {
while (!q.isEmpty() && q.peekLast() < value) {
q.pollLast();
}
p.offerLast(value);
q.offerLast(value);
}
public int pop_front() {
if (p.isEmpty()) return -1;
int res = p.pollFirst();
if (q.peek() == res) q.pollFirst();
return res;
}
}
/**
* Your MaxQueue object will be instantiated and called as such:
* MaxQueue obj = new MaxQueue();
* int param_1 = obj.max_value();
* obj.push_back(value);
* int param_3 = obj.pop_front();
*/var MaxQueue = function () {
this.queue = [];
this.maxValue = -Infinity;
this.maxIdx = -1;
};
/**
* @return {number}
*/
MaxQueue.prototype.max_value = function () {
if (!this.queue.length) return -1;
return this.maxValue;
};
/**
* @param {number} value
* @return {void}
*/
MaxQueue.prototype.push_back = function (value) {
this.queue.push(value);
if (value >= this.maxValue) {
this.maxIdx = this.queue.length - 1;
this.maxValue = value;
}
};
/**
* @return {number}
*/
MaxQueue.prototype.pop_front = function () {
if (!this.queue.length) return -1;
let a = this.queue.shift();
this.maxIdx--;
if (this.maxIdx < 0) {
let tmp = -Infinity;
let id = -1;
for (let i = 0; i < this.queue.length; i++) {
if (this.queue[i] > tmp) {
tmp = this.queue[i];
id = i;
}
}
this.maxIdx = id;
this.maxValue = tmp;
}
return a;
};class MaxQueue {
private:
queue<int> q;
deque<int> d;
public:
MaxQueue() { }
int max_value() {
if (d.empty()) return -1;
return d.front();
}
void push_back(int value) {
while (!d.empty() && d.back() < value) d.pop_back();
d.push_back(value);
q.push(value);
}
int pop_front() {
if (d.empty()) return -1;
int retVal = q.front();
q.pop();
if (d.front() == retVal) d.pop_front();
return retVal;
}
};type MaxQueue struct {
queue []int
deque []int
}
func Constructor() MaxQueue {
return MaxQueue{
queue: make([]int, 0),
deque: make([]int, 0),
}
}
func (this *MaxQueue) Max_value() int {
if len(this.deque) == 0 {
return -1
}
return this.deque[0]
}
func (this *MaxQueue) Push_back(value int) {
for len(this.deque) != 0 && this.deque[len(this.deque)-1] < value {
this.deque = this.deque[:len(this.deque)-1]
}
this.deque = append(this.deque, value)
this.queue = append(this.queue, value)
}
func (this *MaxQueue) Pop_front() int {
if len(this.deque) == 0 {
return -1
}
retVal := this.queue[0]
this.queue = this.queue[1:]
if this.deque[0] == retVal {
this.deque = this.deque[1:]
}
return retVal
}class MaxQueue {
private queue: number[];
private deque: number[];
constructor() {
this.queue = [];
this.deque = [];
}
max_value(): number {
return this.deque[0] ?? -1;
}
push_back(value: number): void {
this.queue.push(value);
while (
this.deque.length !== 0 &&
this.deque[this.deque.length - 1] < value
) {
this.deque.pop();
}
this.deque.push(value);
}
pop_front(): number {
const res = this.queue.shift();
if (res === this.deque[0]) {
this.deque.shift();
}
return res ?? -1;
}
}
/**
* Your MaxQueue object will be instantiated and called as such:
* var obj = new MaxQueue()
* var param_1 = obj.max_value()
* obj.push_back(value)
* var param_3 = obj.pop_front()
*/use std::collections::VecDeque;
struct MaxQueue {
queue: VecDeque<i32>,
deque: VecDeque<i32>,
}
/**
* `&self` means the method takes an immutable reference.
* If you need a mutable reference, change it to `&mut self` instead.
*/
impl MaxQueue {
fn new() -> Self {
Self {
queue: VecDeque::new(),
deque: VecDeque::new(),
}
}
fn max_value(&self) -> i32 {
*self.deque.front().unwrap_or(&-1)
}
fn push_back(&mut self, value: i32) {
self.queue.push_back(value);
while !self.deque.is_empty() && *self.deque.back().unwrap() < value {
self.deque.pop_back();
}
self.deque.push_back(value);
}
fn pop_front(&mut self) -> i32 {
if self.queue.is_empty() {
return -1;
}
let res = self.queue.pop_front().unwrap();
if res == self.deque[0] {
self.deque.pop_front();
}
res
}
}
/**
* Your MaxQueue object will be instantiated and called as such:
* let obj = MaxQueue::new();
* let ret_1: i32 = obj.max_value();
* obj.push_back(value);
* let ret_3: i32 = obj.pop_front();
*/public class MaxQueue {
LinkedList<int> mvq;
Queue<int> q;
public MaxQueue() {
mvq = new LinkedList<int>();
q = new Queue<int>();
}
public int Max_value() {
if (mvq.Count == 0) {
return -1;
}
return mvq.First.Value;
}
public void Push_back(int value) {
q.Enqueue(value);
while (mvq.Count > 0 && mvq.Last.Value < value) {
mvq.RemoveLast();
}
mvq.AddLast(value);
}
public int Pop_front() {
if (q.Count == 0) {
return -1;
}
int v = q.Dequeue();
if (mvq.First.Value == v) {
mvq.RemoveFirst();
}
return v;
}
}
/**
* Your MaxQueue object will be instantiated and called as such:
* MaxQueue obj = new MaxQueue();
* int param_1 = obj.Max_value();
* obj.Push_back(value);
* int param_3 = obj.Pop_front();
*/