单调队列

https://blog.youkuaiyun.com/hjf1201/article/details/78729320 练习题

#include<iostream>
#include<cstdio>
using namespace std;
int a[1000005],q[1000005],num[1000005];
int fmax[1000005],fmin[1000005];
int n,k;
void DPMIN() {
	int head=1,tail=0;
	for(int i=1;i<=n;i++) {
		while(num[head]<i-k+1&&head<=tail) head++;
		while(a[i]<=q[tail]&&head<=tail) tail--;
		num[++tail]=i;
		q[tail]=a[i];
		fmin[i]=q[head];
	}
}
void DPMAX() {
	int head=1,tail=0;
	for(int i=1;i<=n;i++) {
		while(num[head]<i-k+1&&head<=tail) head++;
		while(a[i]>=q[tail]&&head<=tail) tail--;
		num[++tail]=i;
		q[tail]=a[i];
		fmax[i]=q[head];
	}
}
int main() {
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;i++)
	  scanf("%d",&a[i]);
	DPMIN();
	DPMAX();
	for(int i=k;i<=n;i++)
	  printf("%d ",fmin[i]);
	cout<<endl; 
	for(int i=k;i<=n;i++)
	  printf("%d ",fmax[i]);
	return 0;
}