Monotone Queue Sliding Window

#include <iostream>

using namespace std;

const int N = 1000010;

int a[N], q[N];

int main()
{
    int n, k;
    scanf("%d%d", &n, &k);
    for (int i = 0; i < n; i ++ ) scanf("%d", &a[i]);

    int hh = 0, tt = -1;
    for (int i = 0; i < n; i ++ )
    {
        if (hh <= tt && i - k + 1 > q[hh]) hh ++ ;

        while (hh <= tt && a[q[tt]] >= a[i]) tt -- ;
        q[ ++ tt] = i;

        if (i >= k - 1) printf("%d ", a[q[hh]]);
    }

    puts("");

    hh = 0, tt = -1;
    for (int i = 0; i < n; i ++ )
    {
        if (hh <= tt && i - k + 1 > q[hh]) hh ++ ;

        while (hh <= tt && a[q[tt]] <= a[i]) tt -- ;
        q[ ++ tt] = i;

        if (i >= k - 1) printf("%d ", a[q[hh]]);
    }

    puts("");

    return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int N=1000010;
int a[N],q[N];
int main()
{
    int n,k;
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++)
    scanf("%d",&a[i]);
    //维护窗口最小值
    int h=1,t=0;
    for(int i=1;i<=n;i++){
    while(h<=t&&a[q[t]]>=a[i]) t--;
    q[++t]=i;
    if(q[h]<i-k+1) h++;
    if(i>=k) printf("%d ",a[q[h]]);
    }
    cout<<endl;
    //维护窗口最大值
    h=1,t=0;
    for(int i=1;i<=n;i++)
    {
        while(h<=t&&a[q[t]]<=a[i]) t--;
        q[++t]=i;
        if(q[h]<i-k+1) h++;
        if(i>=k)
        printf("%d ",a[q[h]]);
    }
    cout<<endl;
}