1 #include <iostream>
2 #include <cstring>
3 #include <algorithm>
4 #include <cmath>
5 #include <cstdio>
6 using namespace std;
7 struct point {
8 double x,y;
9 };
10 point be[100005],en[100005];
11 int ans[100005];
12 int res[100005];
13
14 double max(double a,double b){
15 return a>b?a:b;
16 }
17 double min(double a,double b){
18 return a<b?a:b;
19 }
20
21 int inter(point a,point b,point c,point d){
22 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))
23 return 0;
24 double h,i,j,k;
25 h = (c.x-a.x)*(b.y-a.y)-(c.y-a.y)*(b.x-a.x);
26 i = (d.x-a.x)*(b.y-a.y)-(d.y-a.y)*(b.x-a.x);
27 j = (a.x-c.x)*(d.y-c.y)-(a.y-c.y)*(d.x-c.x);
28 k = (b.x-c.x)*(d.y-c.y)-(b.y-c.y)*(d.x-c.x);
29 return h*i<0&&j*k<0;
30 }
31 int main()
32 {
33 int n;
34 while(scanf("%d",&n)==1&&n){
35 for(int i=0;i<n;i++)
36 cin>>be[i].x>>be[i].y>>en[i].x>>en[i].y;
37 memset(ans,0,sizeof(ans));
38 memset(res,0,sizeof(res));
39 for(int i=0;i<n;i++){
40 for(int j=i+1;j<n;j++){
41 if(inter(be[i],en[i],be[j],en[j])){
42 ans[i] =1;
43 break;
44 }
45 }
46 }
47 int cnt =0;
48 for(int i=0;i<n;i++){
49 if(!ans[i])
50 res[cnt++] = i+1;
51 }
52 printf("Top sticks: ");
53 for(int i=0;i<cnt-1;i++)
54 printf("%d, ",res[i]);
55 printf("%d.\n",res[cnt-1]);
56
57 }
58 return 0;
59 }
poj 2653 计算几何
时间： 2025-01-10 00:35:32