CF103D Time to Raid Cowavans 根号分治+离线

#include <bits/stdc++.h>   
#define M 550    
#define N 300005  
#define ll long long 
#define setIO(s) freopen(s".in","r",stdin) 
using namespace std;             
int n,m,B; 
ll f[M][M],A[N],output[N];      
struct query
{ 
    int id,k;  
    query(int id=0,int k=0):id(id),k(k){}   
};   
struct Data 
{  
    int id,pos;           
    vector<query>v;    
}p[N];     
int main() 
{  
    int i,j; 
    // setIO("input");                   
    scanf("%d",&n);    
    B=sqrt(n);        
    for(i=1;i<=n;++i) 
    {
        scanf("%lld",&A[i]);   
        p[i].id=(i-1)/B+1;                                    
        if(p[i].id!=p[i-1].id) p[i].pos=1;     
        else p[i].pos=p[i-1].pos+1;   
    }          
    scanf("%d",&m);    
    for(i=1;i<=m;++i) 
    {
        int a,b;
        scanf("%d%d",&a,&b);    
        if(b<B) p[a].v.push_back(query(i, b));    
        else 
        {
            ll re=0;   
            for(j=a;j<=n;j+=b) re+=A[j];   
            output[i]=re;    
        }
    }    
    for(i=n;i>=1;--i) 
    {
        int cur=p[i].pos;
        for(j=1;j<B;++j)   
        {      
            f[p[i].pos][j]=A[i];                                 
            if(i+j<=n) 
            {
                f[p[i].pos][j]+=f[p[i+j].pos][j];                 
            }
        }    
        for(j=0;j<p[i].v.size();++j) 
        {
            output[p[i].v[j].id]=f[p[i].pos][p[i].v[j].k];     
        }
    }   
    for(i=1;i<=m;++i) printf("%lld\n",output[i]);    
    return 0; 
}