【POJ 2823】Sliding Window（单调队列/堆）

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#define pii pair<int,int>
#define mp(i,j) make_pair(i,j)
#define N 1000006
using namespace std;
int n,k;
int a[N];
pii q[N];
int back;
void push(pii a,int d){
	q[++back]=a;
	for(int i=back;i>1&&(d?q[i]>q[i>>1]:q[i]<q[i>>1]);i>>=1)
		swap(q[i],q[i>>1]);
}
void pop(int d){	
	swap(q[1],q[back--]);
	for(int i=1;i<=(back>>1);){
		if(d?q[i]>=max(q[i<<1],q[i<<1|1]):q[i]<=min(q[i<<1],q[i<<1|1]))return;//qaq
		if(((i<<1|1)>back)||(d?q[i<<1]>q[i<<1|1]:q[i<<1]<q[i<<1|1])){
			swap(q[i<<1],q[i]);
			i<<=1;
		}else{
			swap(q[i<<1|1],q[i]);
			i=(i<<1|1);
		}
	}
}
int main() {
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;i++){
		scanf("%d",&a[i]);
		if(i<=k)push(mp(a[i],i),0);
	}
	for(int i=k;i<=n;i++){
		printf("%d ",q[1].first);
		while(back&&q[1].second<=i-k+1)pop(0);
		push(mp(a[i+1],i+1),0);
	}
	puts("");
	back=0;
	for(int i=1;i<=k;i++)push(mp(a[i],i),1);
	for(int i=k;i<=n;i++){
		printf("%d ",q[1].first);
		while(back&&q[1].second<=i-k+1)pop(1);
		push(mp(a[i+1],i+1),1);
	}
	return 0;
}

#include <cstdio>
#define N 1000006
using namespace std;
int n,k;
int a[N],b[N],q[N],head,tail;
int main() {
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;i++)
		scanf("%d",&a[i]);
	for(int i=1;i<=n;i++){
		while(head<tail&&a[i]<q[tail-1])tail--;
		b[tail]=i;
		q[tail++]=a[i];
		while(head<tail&&b[head]<i-k+1)head++;
		if(i>=k)printf("%d ",q[head]);
	}
	puts("");
	tail=head=0;
	for(int i=1;i<=n;i++){
		while(head<tail&&a[i]>q[tail-1])tail--;
		b[tail]=i;
		q[tail++]=a[i];
		while(head<tail&&b[head]<i-k+1)head++;
		if(i>=k)printf("%d ",q[head]);
	}
	return 0;
}