POJ 2823 Sliding Window（单调队列）

#include <cstdio>
#include <algorithm>
using namespace std;
const int MAX_N=1000010; 
int n,k; 
int a[MAX_N],b[MAX_N],deq[MAX_N];
void solve(int u){
    int s=0,t=0;
    for(int i=0;i<n;i++){
        while(s<t&&((a[deq[t-1]]>a[i])^u||a[deq[t-1]]==a[i]))t--;
        deq[t++]=i;
        if(i-k+1>=0){
            b[i-k+1]=a[deq[s]];
            if(deq[s]==i-k+1)s++;
        }
    }for(int i=0;i<=n-k;i++)printf("%d%c",b[i],i==n-k?‘\n‘:‘ ‘);
}
int main(){
    while(~scanf("%d%d",&n,&k)){
        for(int i=0;i<n;i++)scanf("%d",&a[i]);
        solve(0); solve(1);
    }return 0;
}