hdu 6127---Hard challenge（思维）

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long LL;
const LL N=5e4+5;
const double INF=1e18;
struct Node{
    LL x,y;
    LL v;
    double f;
}a[N];

void cal(Node& t)
{
    LL x=t.x;
    LL y=t.y;
    if(x==0) t.f=INF;
    else{
        t.f=(double)y*1.0/(double)x;
    }
}
LL cmp(const Node s1,const Node s2)
{
    return s1.f<s2.f;
}
bool check(Node a,Node b)
{
    if(((a.x*b.y-a.y*b.x)*1.0/a.x)>=0.0)
        return true;
    return false;
}

int main()
{
    LL T; cin>>T;
    while(T--)
    {
        LL n; scanf("%lld",&n);
        LL tot=0;
        for(LL i=1;i<=n;i++)
        {
            scanf("%lld%lld%lld",&a[i].x,&a[i].y,&a[i].v);
            tot+=a[i].v;
            cal(a[i]);
        }
        if(n==1) { puts("0"); continue; }
        sort(a+1,a+n+1,cmp);
        LL ans=0,tmp1=0,tmp2=0;
        tmp1=a[1].v;
        for(LL i=2;i<=n;i++)
        {
           if(!check(a[1],a[i]))
            tmp1+=a[i].v;
        }
       tmp2=tot-tmp1;
       ans=max(tmp1*tmp2,ans);
       if(a[1].x<0) tmp1-=a[1].v;
       for(LL i=2;i<=n;i++)
       {
           if(a[i].x>=0) tmp1+=a[i].v;
           tmp2=tot-tmp1;
           ans=max(tmp1*tmp2,ans);
           if(a[i].x<0) tmp1-=a[i].v;
       }
       printf("%lld\n",ans);
    }
    return 0;
}