Max Points on a Line [leetcode]

思路：对每个点，记录<斜率, 点的个数>对

因为一条直线可以由点+斜率决定，所以相同斜率必在同一条直线上

    int maxPoints(vector<Point> &points) {
        int n = points.size();
        int maxRes = 0;
        for (int i = 0; i < n; i++)
        {
            int samePoint = 0, x0 = 0, curMax = 0;
            map<double, int> kMap;
            for (int j = 0; j < n; j++)
            {
                if (points[i].x == points[j].x && points[i].y == points[j].y) 
                    samePoint++;
                else if (points[i].x == points[j].x) 
                    curMax = max(curMax, ++x0);
                else
                {
                    double k = (points[i].y - points[j].y + 0.0) / (points[i].x - points[j].x);
                    curMax = max(curMax, ++kMap[k]);
                }
            }
            maxRes = max(curMax + samePoint, maxRes);
        }
        return maxRes;
    }