凸包模板 POJ1873

 // 凸包模板 POJ1873
 // n=15所以可以按位枚举求凸包，再记录数据

 #include <iostream>
 #include <cstdio>
 #include <cstdlib>
 #include <algorithm>
 #include <vector>
 #include <math.h>
 using namespace std;
 #define LL long long
 typedef pair<int,int> pii;
 const double inf = 0x3f3f3f3f;
 const LL MOD =100000000LL;
 const int N =;
 #define clc(a,b) memset(a,b,sizeof(a))
 const double eps = 1e-;
 void fre() {freopen("in.txt","r",stdin);}
 void freout() {freopen("out.txt","w",stdout);}
 inline int read() {int x=,f=;char ch=getchar();while(ch>''||ch<'') {if(ch=='-') f=-; ch=getchar();}while(ch>=''&&ch<='') {x=x*+ch-'';ch=getchar();}return x*f;}

 int sgn(double x){
     if(fabs(x) < eps)return ;
     if(x < )return -;
     else return ;
 }

 struct Point{
     double x,y;
     Point(){}
     Point(double _x,double _y){
         x = _x;y = _y;
     }
     Point operator -(const Point &b)const{
         return Point(x - b.x,y - b.y);
     }
     double operator ^(const Point &b)const{
         return x*b.y - y*b.x;
     }
     double operator *(const Point &b)const{
         return x*b.x + y*b.y;
     }
     friend bool operator<(const Point &a,const Point &b){
         if(fabs(a.y-b.y)<eps) return a.x<b.x;
         return a.y<b.y;
     }
     friend double dis2(Point a){
         return a.x*a.x+a.y*a.y;
     }
 };

 double dis(Point a,Point b){
     return sqrt(dis2(a-b));
 }
 double mult(Point a,Point b,Point o){
     return (a.x-o.x)*(b.y-o.y)>=(b.x-o.x)*(a.y-o.y);
 }

 Point P[];
 double v[],l[];

 double graham(Point p[],int n,Point q[]){
      int top=;
      sort(p,p+n);
      if(n==) return ;
      q[]=p[];
      if(n==) return ;
      q[]=p[];
      if(n==) return dis(p[],p[])*;
      q[]=p[];
      for(int i=;i<n;i++){
          while(top&&(mult(p[i],q[top],q[top-]))) top--;
          q[++top]=p[i];
      }
      int len=top;
      q[++top]=p[n-];
      for(int i=n-;i>=;i--){
          while(top!=len&&(mult(p[i],q[top],q[top-]))) top--;
          q[++top]=p[i];
      }
      double c=dis(q[],q[top-]);
      for(int i=;i<top-;i++)
         c+=dis(q[i],q[i+]);
     return c;
 }

 int n;
 int b[],a[];
 Point p[],ch[];
 int main(){
     int cas=;
     while(~scanf("%d",&n),n){
         for(int i=;i<n;i++){
             double x,y;
             scanf("%lf%lf%lf%lf",&x,&y,&v[i],&l[i]);
             P[i]=Point(x,y);
         }
         int k,cnt;
         double ans=;
         int minn_cnt=;
         double sum,len,minn=inf;
         for(int st=;st<(<<n);st++){
             sum=,len=,k=,cnt=;

             for(int i=;i<n;i++){
                if(st&(<<i)){
                    sum+=v[i];
                    len+=l[i];
                    b[++cnt]=i+;
                }
                else{
                   p[k++]=P[i];
                }
             }
             double lenn=graham(p,k,ch);
             if(lenn>len) continue;
             if(sum<minn||(sum==minn&&cnt<minn_cnt)){
                 minn=sum;
                 minn_cnt=cnt;
                 ans=len-lenn;
                 for(int i=;i<=cnt;i++){
                     a[i]=b[i];
                 }
             }
         }
         printf("Forest %d\n",cas++);
         printf("Cut these trees:");
         for(int i=;i<=minn_cnt;i++){
             printf(" %d",a[i]);
         }
         printf("\n");
         printf("Extra wood: ");
         printf("%.2f\n",ans);
         printf("\n");
     }
     return ;
 }