149. Max Points on a Line

Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.

class Solution {
public:
    int maxPoints(vector<Point>& points) {
        unordered_map<float,int> mp;
        int maxNum = 0;
        for(int i=0;i<points.size();i++)
        {
            mp.clear();
            mp[INT_MAX] = 0; //当只有一个元素时，这个赋值有用
            int duplicate = 1;
            for(int j=0;j<points.size();j++)
            {
                if(j==i)
                  continue;
                if(points[i].x == points[j].x&&points[i].y == points[j].y)
                {
                    duplicate++;
                    continue;
                }
                float k = points[i].x == points[j].x ?  INT_MAX : (float)(points[i].y - points[j].y)/(points[i].x - points[j].x);
                mp[k]++;
 
            }
            unordered_map<float,int>::iterator it = mp.begin();
            for(;it!=mp.end();it++)
            {
              if(it->second + duplicate > maxNum)
                maxNum = it->second + duplicate;
            }
        }
        return maxNum;
    }
};