Lining Up Rabbit hunt poj 1118 poj 2606 点共线问题。

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <string>
 7 #include <vector>
 8 #include <set>
 9 #include <map>
10 #include <queue>
11 #include <stack>
12 using namespace std;
13 typedef long  long LL;
14 const LL INF = 0x4fffffff;
15 const double EXP= 1e-6;
16 const LL MOD = 1e9+7;
17 const int MS= 1e5 + 5 ;
18 
19 
20 struct point
21 {
22     int x;
23     int y;
24 }points[MS];
25 
26 double k[MS];
27 
28 int cmp(const point &a,const point &b)
29 {
30     if(a.x != b.x)
31         return a.x < b.x;
32     return a.y < b.y;
33 }
34 
35 double slope(point a,point b)
36 {
37     if(a.x == b.x)
38         return INF;
39     double px = a.x - b.x;
40     double py = a.y - b.y;
41     return py / px;
42 }
43 
44 int main()
45 {
46     int n;
47     int i,j,cnt,t,maxv;
48     while(scanf("%d",&n) != EOF && n)
49     {
50         for(i = 0;i < n;i++)
51             scanf("%d%d",&points[i].x,&points[i].y);
52         sort(points,points+n,cmp);
53         maxv = -1;
54         for(i=0;i < n;i++)
55         {
56             t=0;
57             for(j = i+1;j < n;j++)
58             {
59                 k[t++] = slope(points[i],points[j]);
60             }
61             sort(k,k+t);
62             for(j = 1,cnt = 1;j < t;j++)
63             {
64                 if(fabs(k[j]-k[j-1]) < EXP)
65                     cnt++;
66                 else
67                     cnt=1;
68                 if(cnt > maxv)
69                     maxv = cnt;
70             }
71         }
72         printf("%d\n",maxv+1);
73     }
74     return 0;
75 }