AOJ 796.数三角形

 1 #include <cstdio>
 2 #include <algorithm>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <string>
 6 #include <iostream>
 7 #include <vector>
 8 #include <list>
 9 #include <stack>
10 using namespace std;
11  
12 #define REP(n) for(int o=0;o<n;o++)
13  
14 pair<int,int> p[205];
15 bool Do() {
16     int n;
17     if(scanf("%d",&n) == EOF)
18         return false;
19     REP(n) {
20         int x,y;
21         scanf("%d%d",&x,&y);
22         p[o] = pair<int,int>(x,y);
23     }
24     int cnt = 0;
25     for(int i = 0;i < n;i++)
26         for(int j = i + 1;j < n;j++)
27             for(int k = j + 1;k < n;k++) {
28                 if(i < j&&j < k) {
29                     pair<int,int >a = p[i],b = p[j],c = p[k];
30                     if(!(
31                         (a.first == b.first&&a.first == c.first) ||
32                         (a.second == b.second&&a.second == c.second) ||
33                         ((double)(a.first - b.first) / (double)(a.second - b.second) ==
34                             (double)(c.first - b.first) / (double)(c.second - b.second))
35                         )) {
36                         cnt++;
37                         //printf("%d %d %d\n",i,j,k);
38                     }
39                 }
40             }
41     printf("%d\n",cnt);
42  
43     return true;
44 }
45  
46 int main() {
47     while(Do());
48     return 0;
49 }