Max Points on a Line

class Solution {
public:
    int maxPoints(vector<Point> &points) {
        if(points.size() <= 2) return points.size();
        
        int maxpoint = 0;
        
        unordered_map<double, int> hash;
    
        for(int i=0; i<points.size()-1; i++)
        {
            hash.clear();
            int same = 0;
            int infinity = 1;
            int curmax = 0;
            
            for(int j=i+1; j<points.size(); j++)
            {
                if(points[j].x == points[i].x)
                {
                    if(points[j].y == points[i].y)
                        same++;
                    else
                       infinity++; 
                }
                else
                {
                    double slope = 1.0*(points[j].y - points[i].y)/(points[j].x - points[i].x);
                    if(hash.count(slope) > 0)
                        hash[slope]++;
                    else
                        hash[slope] = 2;
                    
                    curmax = max(curmax, hash[slope]);
                }
            }
            curmax = max(curmax, infinity);
            curmax += same;
            
            maxpoint = max(maxpoint, curmax);
        }
        return maxpoint;
    }
};

infinity代表无穷大的slope。