poj 2653 计算几何

 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