hdu 6444 长度不超过K的最大字段和

参考博客：

https://blog.csdn.net/sinat_34550050/article/details/52274141

代码：

#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
const int N =1e4+5;
int n,m,k;
ll S;
ll a[N];
int vis[N];
int tot;

struct node
{
    int id;
    ll val;
};

vector<ll >huan[N];
int len[N];
ll sum[N];
ll num[N*2];
ll ss[N*2];
int q[N*2];

void solve(int id,ll &maxx)
{
    int nn=0;
    for(int i=0; i<len[id]; i++)
    {
        num[++nn]=huan[id][i];
    }
    for(int i=0; i<len[id]; i++)
    {
        num[++nn]=huan[id][i];
    }

    memset(ss,0,sizeof(ss));
    for(int i=1; i<=nn; i++)
    {
        ss[i]=ss[i-1]+num[i];
    }
    int sz=len[id];

    ll Ans=0;
    int K=m%sz;
    int head,tail;
    head=tail=0;
    for(int i=1; i<=nn; i++)
    {
        while(head<tail&&ss[i-1]<ss[q[tail-1]]) tail--;
        q[tail++]=i-1;
        while(head<tail&&i-q[head]>K) head++;
        Ans=max(Ans,ss[i]-ss[q[head]]);
    }
    if(sum[id]>0) Ans+=(m/sz)*sum[id];
    maxx=max(maxx,Ans);

    Ans=0;
    K=sz;
    head=tail=0;
    for(int i=1; i<=nn; i++)
    {
        while(head<tail&&ss[i-1]<ss[q[tail-1]]) tail--;
        q[tail++]=i-1;
        while(head<tail&&i-q[head]>K) head++;
        Ans=max(Ans,ss[i]-ss[q[head]]);
    }

    if(sum[id]>0)
    {
        int cnt=m/sz-1;
        if(cnt<0) cnt=0;
        Ans+=1ll*cnt*sum[id];
    }
    // cout<<"Ans "<<Ans<<endl;
    maxx=max(maxx,Ans);
}

int main()
{
    int T;
    scanf("%d",&T);
    int kk=0;
    while(T--)
    {
        scanf("%d %lld %d %d",&n,&S,&m,&k);
        for(int i=0; i<n; i++) scanf("%lld",&a[i]);
        memset(vis,0,sizeof(vis));
        memset(len,0,sizeof(len));
        memset(sum,0,sizeof(sum));
        for(int i=1; i<=n; i++) huan[i].clear();
        tot=0;

        for(int i=0; i<n; i++)
        {
            if(vis[i]) continue;
            ll ss=0;
            ++tot;
            for(int j=i;; j=(j+k)%n)
            {
                if(vis[j]) break;
                vis[j]=1;
                huan[tot].push_back(a[j]);
                len[tot]++;
                sum[tot]+=a[j];
            }
        }

        /*
        for(int i=1;i<=tot;i++){
            cout<<"*********"<<endl;
            for(int j=0;j<huan[i].size();j++) cout<<huan[i][j]<<" ";
            cout<<endl;
        }
        */

        ll maxx=0;
        for(int i=1; i<=tot; i++)
        {
            solve(i,maxx);
        }
        if(maxx>=S)
        {
            printf("Case #%d: %d\n",++kk,0);
        }
        else printf("Case #%d: %lld\n",++kk,S-maxx);
    }
    return 0;
}

/*

1
5 1000 6 1
1 1 -1 -1 1

*/