points.cpp

#include<iostream>
#include<set>
#include<utility>
#include<vector>
#include<map>

using namespace std;


  struct Point {
      int x;
      int y;
      Point() : x(0), y(0) {}
      Point(int a, int b) : x(a), y(b) {}
  };

int maxPoints(vector<Point> &points) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        //15:43
        map<pair<float,float>,set<int> >m;
        map<int,set<int> > n;
        for(int i=0;i<points.size();i++)
        {
            for(int j=i+1;j<points.size();j++)
            {
                float k,t;
                if(points[i].x!=points[j].y)
                {
                    k=(points[i].y-points[j].y)/((float)(points[i].x-points[j].x));
                    t=points[i].y-k*points[i].x;
                    pair<float,float> p=make_pair(k,t);
                    if(m.find(p)==m.end())
                        m[p]=set<int>();
                    m[p].insert(i);
                    m[p].insert(j);
                    
                }
                else
                {
                    if(n.find(points[i].x)==n.end())
                        n[points[i].x]=set<int>();
                    n[points[i].x].insert(i);
                    n[points[i].x].insert(j);
                }
            }
        }
        int maxn=0;
        for(map<pair<float,float>,set<int> >::iterator it=m.begin();it!=m.end();it++)
            maxn=max(maxn,(int)it->second.size());
        for(map<int,set<int> >::iterator it=n.begin();it!=n.end();it++)
            maxn=max(maxn,(int)it->second.size());
        return maxn;
    }

main()
{

}