poj1118 469ms 0(n^3)飘过

#include<cstdio>
using namespace std;
struct point
{
    int x;
    int y;
} points[705];
int main()
{
    int n;
    while(scanf("%d",&n),n)
    {
        for(int i = 0; i<n; ++i)
            scanf("%d%d",&points[i].x,&points[i].y);
        int cnt = 0,ans = 0;
        for(int i = 0; i<n; ++i)
        {
            for(int j = i+1; j<n; ++j)
            {
                cnt = 2;
                for(int k = j+1; k<n; ++k)
                {
                    if((points[j].y-points[i].y)*(points[k].x-points[j].x)==(points[k].y-points[j].y)*(points[j].x-points[i].x))
                        cnt++;
                }
                if(cnt>ans)
                    ans = cnt;
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}