PAT (Advanced Level) 1037. Magic Coupon (25)

#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<cstdio>
#include<map>
#include<queue>
#include<vector>
using namespace std;

const int maxn=100000+10;
int n,m;
long long a[maxn];
long long b[maxn];

bool cmp(const long long &a,const long long &b)
{
    return a>b;
}

int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++) scanf("%lld",&a[i]);
    scanf("%d",&m);
    for(int i=1;i<=m;i++) scanf("%lld",&b[i]);
    sort(a+1,a+1+n);
    sort(b+1,b+1+m);
    long long ans=0;
    for(int i=1;i<=min(m,n);i++)
    {
        if(a[i]>=0) break;
        if(b[i]>=0) break;
        ans=ans+a[i]*b[i];
    }
    sort(a+1,a+1+n,cmp);
    sort(b+1,b+1+m,cmp);

    for(int i=1;i<=min(m,n);i++)
    {
        if(a[i]<=0) break;
        if(b[i]<=0) break;
        ans=ans+a[i]*b[i];
    }
    printf("%lld\n",ans);
    return 0;
}