poj 2653 计算几何

 #include <iostream>
 #include <cstring>
 #include <algorithm>
 #include <cmath>
 #include <cstdio>
 using namespace std;
 struct  point {
     double x,y;
 };
 point be[],en[];
 int ans[];
 int res[];

 double max(double a,double b){
     return a>b?a:b;
 }
 double min(double a,double b){
     return a<b?a:b;
 }

 int inter(point a,point b,point c,point d){
     if(min(a.x,b.x)>max(c.x,d.x)||min(a.y,b.y)>max(c.y,d.y)||min(c.x,d.x)>max(a.x,b.x)||min(c.y,d.y)>max(a.y,b.y))
         return ;
     double h,i,j,k;
     h = (c.x-a.x)*(b.y-a.y)-(c.y-a.y)*(b.x-a.x);
     i = (d.x-a.x)*(b.y-a.y)-(d.y-a.y)*(b.x-a.x);
     j = (a.x-c.x)*(d.y-c.y)-(a.y-c.y)*(d.x-c.x);
     k = (b.x-c.x)*(d.y-c.y)-(b.y-c.y)*(d.x-c.x);
     return h*i<&&j*k<;
 }
 int main()
 {
     int n;
     while(scanf("%d",&n)==&&n){
         for(int i=;i<n;i++)
             cin>>be[i].x>>be[i].y>>en[i].x>>en[i].y;
         memset(ans,,sizeof(ans));
         memset(res,,sizeof(res));
         for(int i=;i<n;i++){
             for(int j=i+;j<n;j++){
                 if(inter(be[i],en[i],be[j],en[j])){
                     ans[i] =;
                     break;
                 }
             }
         }
         int cnt =;
         for(int i=;i<n;i++){
             if(!ans[i])
                 res[cnt++] = i+;
         }
         printf("Top sticks: ");
         for(int i=;i<cnt-;i++)
             printf("%d, ",res[i]);
         printf("%d.\n",res[cnt-]);

     }
     return ;
 }