class Point {
public:double _x, _y;Point(double x, double y): _x(x), _y(y) {};
};class Line {
public:static constexpr double _epsilon = 0.0001;double _slope, _intercept;bool _infi_slope = false;Line(Point p, Point q) {if (fabs(p._x - q._x) > _epsilon) {_slope = (p._y - q._y) / (p._x - q._x);_intercept = p._y - _slope * p._x;} else {_infi_slope = true;_intercept = p._x;}}static double floorToNearestEpsilon(double d) {int r = (int)(d / _epsilon);return ((double)r) * _epsilon;}bool isEquivalent(double a, double b) {return (fabs(a - b) < _epsilon);}bool isEquivalent(Line other) {if (isEquivalent(_slope, other._slope) && isEquivalent(_intercept, other._intercept) && (_infi_slope == other._infi_slope)) {return true;}return false;}
};class Solution {
public:Line findBestLine(vector<Point> &points) {Line res(points[0], points[1]);int bestCnt = 0;unordered_map<double, vector<Line> > m;for (int i = 0; i < (int)points.size(); ++i) {for (int j = i + 1; j < (int)points.size(); ++j) {Line line(points[i], points[j]);insertLine(m, line);int cnt = countEquivalentLines(m, line);if (cnt > bestCnt) {res = line;bestCnt = cnt;}}}return res;}void insertLine(unordered_map<double, vector<Line> > &m, Line &line) {vector<Line> lines;double key = Line::floorToNearestEpsilon(line._slope);if (m.find(key) != m.end()) {lines = m[key];} else {m[key] = lines;}lines.push_back(line);}int countEquivalentLines(unordered_map<double, vector<Line> > &m, Line &line) {double key = Line::floorToNearestEpsilon(line._slope);double eps = Line::_epsilon;return countEquivalentLines(m[key], line) + countEquivalentLines(m[key - eps], line) + countEquivalentLines(m[key + eps], line);}int countEquivalentLines(vector<Line> &lines, Line &line) {if (lines.empty()) return 0;int res = 0;for (auto &a : lines) {if (a.isEquivalent(line)) ++res;}return res;}
};