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#include "leetcode.h"
class Point { // basic coordinate geometry
public:
double x, y;
Point(double x, double y) {
this->x = x;
this->y = y;
}
};
class Solution {
public:
int maxPoints(vvd(int) & points) {
int n = points.size(), ans = 0;
if (n <= 2) // 2 or less means points are always collinear
return n;
vector<Point> coordinates;
for (auto &i : points) {
Point k = Point((double)i[0], (double)i[1]);
coordinates.push_back(k);
}
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++) {
int cnt = 0;
for (int k = 0; k < n; k++)
if (i != j && j != k && i != k)
if (isCollinear(coordinates[i], coordinates[j], coordinates[k]))
cnt++;
ans = max(cnt + 2, ans);
}
return ans;
}
private:
bool isCollinear(Point a, Point b,
Point c) { // checks if 3 given points lie on same line
double i = (b.y - a.y) / (b.x - a.x);
double j = (c.y - b.y) / (c.x - b.x);
return i == j;
}
};
int main() {
Solution obj;
vvd(int) points1 = {{1, 1}, {2, 2}, {3, 3}},
points2 = {{1, 1}, {3, 2}, {5, 3}, {4, 1}, {2, 3}, {1, 4}};
cout << obj.maxPoints(points1) << endl; // expect: 3
cout << obj.maxPoints(points2) << endl; // expect: 4
}
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