【bzoj1610】【Usaco2008 Feb】Line连线游戏

#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<math.h>
#include<map>
using namespace std;
int n,x[205],y[205];
map<double,int>vis;
int main()
{
scanf("%d",&n);
for (int i=1;i<=n;i++)
{
scanf("%d%d",&x[i],&y[i]);
}
int ans=0;
int flagx=0;
int flagy=0;
for (int i=1;i<=n;i++)
for (int j=1;j<=n;j++)
{
if (i==j) continue;
int yy=y[i]-y[j];
int xx=x[i]-x[j];
if (xx==0)
{
if (!flagx)
ans++;
flagx=1;
}
else if (yy==0)
{
if (!flagy)
ans++;
flagy=1;
}
else
{
double hh=(double)yy/(double)xx;
if (vis[hh]==0)
ans++;
//printf("%.6lf\n",hh);
vis[hh]=1;
}
}
printf("%d\n",ans);
}