油滴拓展

#include<bits/stdc++.h> 
using namespace  std;
int c[10];
int m,n,xs,xe,ys,ye;
double sum;
bool b[10];
int a[2000][20];
int x[10];
int y[10];

double dis(int i,int j)
{

    return(sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j])));
}

int dfs(int xx)
{
    int i;
    if (xx==n)
    {
        m++;
        for
 
 (i=1;i<=n;i++) a[m][i]=c[i];
        return 0;
    }
    for (i=1;i<=n;i++) if (b[i])
    {
        b[i]=false;
        c[xx+1]=i;
        dfs(xx+1);
        b[i]=true;      
    }
}

double min(double t1,double t2)
{
    if (t1>t2) return(t2); else return(t1);
}
double summ(int t)
{
    int
 
 i,j;
    double r[10];
    double s;
    for (i=1;i<=n;i++) r[i]=-1.0;   
    for (i=1;i<=n;i++)    
     {
        s=INT_MAX;
        s=min(s,abs(x[a[t][i]]-xs));
        s=min(s,abs(x[a[t][i]]-xe));
        s=min(s,abs(y[a[t][i]]-ys));
        s=min(s,abs(y[a[t][i]]-ye));    
        for (j=1
 
;j<=n;j++) 
          {
              if (dis(a[t][i],j)<r[j]) 
              {
                  s=0;
                  break;    
              }
              if ((r[j]!=-1)&(a[t][i]!=j)) s=min(s,(dis(a[t][i],j)-r[j]));  
          } 
        r[i]=s;     
     }
     s=0;
     for (i=1;i<=n;i++) if (r[a[t][i]]!=-1) s=s+r[a[t][i]]*r[a[t][i]]*M_PI ;
     return(s);

}

int main()
{
    int i,j;
    cin>>n;
    m=0;
    for (i=1;i<=n;i++) b[i]=true;
    dfs(0);
    cin>>xs>>ys>>xe>>ye;
    for (i=1;i<=n;i++) cin>>x[i]>>y[i];
    sum=-1; 
    for (i=1;i<=m;i++) 
    {
        if (summ(i)>sum) sum=summ(i);
    }
    sum=(double)abs(xs-xe)*abs(ys-ye)-sum;
    cout<<(int)(sum+0.5);
}