FZU2148——叉积——Moon Game

http://acm.fzu.edu.cn/problem.php?pid=2148

　　

/************************************************
* Author        :Powatr
* Created Time  :2015-8-23 18:28:55
* File Name     :H.cpp
 ************************************************/

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std;

#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int MAXN = 1e2 + 10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
int S(int x1, int y1, int x2, int y2, int x3, int y3){
    return abs(x1*y2 + x2*y3 + x3*y1 - x1*y3 - x2*y1 - x3*y2);
}
int a[MAXN];
int b[MAXN];
int main(){
    int T;
    scanf("%d", &T);
    int n;
    for(int cas = 1; cas <= T; cas++){
          scanf("%d", &n);
          int cout = 0;
          for(int i = 1; i <= n; i++)
              scanf("%d%d", &a[i], &b[i]);
          for(int i = 1; i <= n; i++){
              for(int j = i + 1; j <= n; j++){
                  for(int k = j + 1; k <= n; k++){
                      for(int p = k + 1; p <= n; p++){
                          int x1 = a[i], y1 = b[i];
                          int x2 = a[j], y2 = b[j];
                          int x3 = a[k], y3 = b[k];
                          int x4 = a[p], y4 = b[p];
                          int S1 = S(x1, y1, x2, y2, x3, y3);
                          int S2 = S(x1, y1, x2, y2, x4, y4);
                          int S3 = S(x1, y1, x3, y3, x4, y4);
                          int S4 = S(x2, y2, x3, y3, x4, y4);
        if(S1 + S2 + S4 == S3 || S1 + S3 + S4 == S2 || S1 + S2 + S3 == S4 || S2 + S3 + S4 == S1);
        else cout++;
                      }
                  }
              }
          }
          printf("Case %d: %d\n", cas, cout);
    }
    return 0;
}