埃氏筛+线段树——cf731F

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define N 200005
int cnt[N],n;

#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
ll num[N<<2];
void update(int pos,int v,int l,int r,int rt){
    if(l==r){
        num[rt]+=v;
        return;
    }
    int m=l+r>>1;
    if(pos<=m)update(pos,v,lson);
    else update(pos,v,rson);
    num[rt]=num[rt<<1]+num[rt<<1|1];
}
ll query(int L,int R,int l,int r,int rt){
    if(L<=l && R>=r){
        return num[rt];
    }
    int m=l+r>>1;
    ll res=0;
    if(L<=m)res+=query(L,R,lson);
    if(R>m)res+=query(L,R,rson);
    return res;
}

int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        int x;scanf("%d",&x);
        cnt[x]++;
    }
    
    ll ans=0;
    for(ll i=200000;i>=1;i--)if(cnt[i]){
        ll tmp=0;
        update(i,cnt[i],1,200000,1);
        for(ll j=1;j*i<=200000;j++)
            tmp+=query(j*i,min(200000ll,(j+1)*i-1),1,200000,1)*i*j;
        ans=max(ans,tmp);
    }
    cout<<ans<<endl;
}