codeforces 672C - Recycling Bottles 贪心水题

感觉很简单，就是讨论一下

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <math.h>
using namespace std;
typedef pair<double,int>pii;
const int N = 1e5+;
double x[N],y[N];
pii a[N],b[N];
double dis(double x1,double y1,double x2,double y2){
    return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
int main(){
    double ax,ay,bx,by,tx,ty,sum=;
    int n;
    scanf("%lf%lf%lf%lf%lf%lf",&ax,&ay,&bx,&by,&tx,&ty);
    scanf("%d",&n);
    for(int i=;i<=n;++i)
      scanf("%lf%lf",&x[i],&y[i]);
    for(int i=;i<=n;++i){
      a[i].second=b[i].second=i;
      double k1=dis(ax,ay,x[i],y[i]);
      double k2=dis(bx,by,x[i],y[i]);
      double k3=dis(tx,ty,x[i],y[i]);
      sum+=k3*;
      a[i].first=k1-k3;
      b[i].first=k2-k3;
    }
    sort(a+,a++n);
    sort(b+,b++n);
    if(a[].first>=&&b[].first>=){
        sum+=min(a[].first,b[].first);
    }
    else if(a[].first<&&b[].first>=){
        sum+=a[].first;
    }
    else if(a[].first>=&&b[].first<){
        sum+=b[].first;
    }
    else {
       if(a[].second!=b[].second){
        sum+=a[].first+b[].first;
       }
       else {
         if(n==)sum+=min(a[].first,b[].first);
         else {
            double k1=a[].first+b[].first;
            double k2=b[].first+a[].first;
            k1=min(min(k1,k2),min(a[].first,b[].first));
            sum+=k1;
         }
       }
    }
    printf("%.8f\n",sum);
    return ;
}