BZOJ 1610 连线游戏

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#define maxv 250
#define inf 0x7f7f7f7f
using namespace std;
struct pnt
{
    double x,y;
}p[maxv];
int n,cnt=0;
double stack[200500];
int main()
{
    scanf("%d",&n);
    for (int i=1;i<=n;i++)
        scanf("%lf%lf",&p[i].x,&p[i].y);
    for (int i=1;i<=n;i++)
        for (int j=i+1;j<=n;j++)
        {
            if (p[i].x!=p[j].x) stack[++cnt]=(p[j].y-p[i].y)/(p[j].x-p[i].x);
            else stack[++cnt]=inf;
        }
    sort(stack+1,stack+cnt+1);
    int ret=1;
    for (int i=2;i<=cnt;i++)
        if (fabs(stack[i]-stack[i-1])>1e-8) ret++;
    printf("%d\n",ret);
    return 0;
}