leetcode[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.

/**

 * Definition for a point.

 * struct Point {

 *     int x;

 *     int y;

 *     Point() : x(0), y(0) {}

 *     Point(int a, int b) : x(a), y(b) {}

 * };

 */

class Solution {

public:

int maxPoints(vector<Point> &points) {

    if(points.size()<3)return points.size();

    int sizeMax=0;

    for(int i=0;i<points.size();i++)

    {

        int repeat=1;

        map<double,int> smap;

        smap.clear();

        for(int j=0;j<points.size();j++)

        {

            if(i==j)continue;

            if(points[i].x==points[j].x&&points[i].y==points[j].y)

            {

                repeat++;

                continue;

            }

            double k=points[i].x==points[j].x?INT_MAX:double(points[j].y-points[i].y)/(points[j].x-points[i].x);

            smap[k]++;

        }

        if(smap.size()==0)

        {

            sizeMax=sizeMax>repeat?sizeMax:repeat;

            continue;

        }

        for(map<double,int>::iterator iter=smap.begin();iter!=smap.end();iter++)

        {

            sizeMax=sizeMax>(iter->second+repeat)?sizeMax:(iter->second+repeat);

        }

    }

    return sizeMax;

}

};