ps:遗忘了原理，可以参考下文
https://www.acwing.com/solution/content/2499/

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
#define INF 0x3f3f3f3f

using namespace std;

const int N=1e6;

int n,k;
int head,tail,p[N],q[N],a[N];

void get_max(){
    head=1,tail=0;
    for(int i=1;i<=n;i++){
        while(head<=tail&&q[tail]<=a[i])    tail--;
        q[++tail]=a[i];
        p[tail]=i;
        while(p[head]<=i-k) head++;
        if(i>=k)    printf("%d ",q[head]);
    }
    printf("\n");
}

void get_min(){
    head=1,tail=0;
    for(int i=1;i<=n;i++){
        while(head<=tail&&q[tail]>=a[i])    tail--;
        q[++tail]=a[i];
        p[tail]=i;
        while(p[head]<=i-k) head++;
        if(i>=k)    printf("%d ",q[head]);
    }
    printf("\n");
}

int main(){
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++)   scanf("%d",&a[i]);
    get_min();
    get_max();
    return 0;
}