POJ 2280&&hdu 1661

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<set>
 6 #include<stdio.h>
 7 #include<stdlib.h>
 8 #include<math.h>
 9 #define clc(a,b) memset(a,b,sizeof(a))
10 #define eps 1e-8
11 typedef long long LL;
12 const int mod=47000;
13 const int inf=0x3f3f3f3f;
14 using namespace std;
15 #define N 100010
16 
17 struct node
18 {
19     int x,y,r;
20     double ang;
21 }v[1010],rem[1010];
22 
23 int cmp(const struct node a,const struct node b)
24 {
25     if(a.ang<b.ang)
26         return 1;
27     else
28         return 0;
29 }
30 
31 int sig (double a)
32 {
33     if(fabs(a)<eps)
34         return 0;
35     else if(a>0)
36         return 1;
37     else
38         return -1;
39 }
40 
41 int cross(struct node a,struct node b,struct node c)
42 {
43     return (b.x-a.x)*(c.y-a.y)-(c.x-a.x)*(b.y-a.y);
44 }
45 
46 int main()
47 {
48     int n;
49     while(~scanf("%d",&n)&&n)
50     {
51         int ans=0;
52         for(int i=0;i<n;i++)
53         {
54             scanf("%d%d%d",&v[i].x,&v[i].y,&v[i].r);
55             rem[i]=v[i];
56         }
57         for(int i=0;i<n;i++)
58         {
59             for(int j=0;j<n;j++)
60             {
61                 v[j]=rem[j];
62                 if(v[j].r==1)
63                 {
64                     v[j].x=rem[i].x*2-v[j].x;
65                     v[j].y=rem[i].y*2-v[j].y;
66                 }
67                 v[j].ang=atan2(v[j].y-rem[i].y,v[j].x-rem[i].x);
68             }
69             swap(v[i],v[0]);
70             sort(v+1,v+n,cmp);
71             for(int j=1,t=2;j<n&&sig(v[j].ang)<=0;j++)
72             {
73                 int on=2;
74                 for( ;t<n&&cross(v[0],v[j],v[t])>=0;t++)
75                 {
76                     if(cross(v[0],v[j],v[t])==0)
77                     on++;
78                 }
79                 ans=max(ans,max(t-j+1,n-(t-j+1)+on));
80             }
81         }
82         cout<<ans<<endl;
83     }
84     return 0;
85 }