FZU 2148 Moon Game --判凹包

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <algorithm>
using namespace std;
#define N 1007
#define M 33

struct Point
{
    double x,y;
}p[34];

double calc_area(Point a,Point b,Point c)  //叉积求三角形面积
{
    return fabs(a.x*b.y + c.x*a.y + b.x*c.y - c.x*b.y - a.x*c.y - b.x*a.y)*0.5;
}

int main()
{
    int t,i,n;
    int j,k,h;
    int cs = 1;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(i=0;i<n;i++)
            scanf("%lf%lf",&p[i].x,&p[i].y);
        int cnt = 0;
        for(i=0;i<n-3;i++)
        {
            for(j=i+1;j<n-2;j++)
            {
                for(k=j+1;k<n-1;k++)
                {
                    for(h=k+1;h<n;h++)
                    {
                        double Area1 = calc_area(p[i],p[j],p[k]);
                        double Area2 = calc_area(p[i],p[j],p[h]);
                        double Area3 = calc_area(p[j],p[k],p[h]);
                        double Area4 = calc_area(p[i],p[k],p[h]);
                        //printf("%lf %lf %lf %lf\n",Area1,Area2,Area3,Area4);
                        if(fabs(Area1-Area2-Area3-Area4) < eps)
                            continue;
                        if(fabs(Area2-Area3-Area4-Area1) < eps)
                            continue;
                        if(fabs(Area3-Area1-Area2-Area4) < eps)
                            continue;
                        if(fabs(Area4-Area1-Area2-Area3) < eps)
                            continue;
                        cnt++;
                    }
                }
            }
        }
        printf("Case %d: %d\n",cs++,cnt);
    }
    return 0;
}