Given

n

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

public class Solution {
    public int maxPoints(Point[] points) {
        if(points.length <= 0) return 0;
        if(points.length <= 2) return points.length;
        int result = 0;
        for(int i = 0; i < points.length; i++){
            HashMap<String, Integer> hm = new HashMap<>();
            int samex = 1;
            int samep = 0;
            for(int j = 0; j < points.length; j++){
                if(j != i){
                    if((points[j].x == points[i].x) && (points[j].y == points[i].y)){
                        samep++;
                    }
                    if(points[j].x == points[i].x){
                        samex++;
                        continue;
                    }
                    int diffY = points[j].y - points[i].y;
                    int diffX = points[j].x - points[i].x;
                    int gcd = gcd(diffY, diffX);
                    String str = diffY / gcd + "-" + diffX / gcd;
                    if(hm.containsKey(str)){
                        hm.put(str,hm.get(str) + 1);
                    }else{
                        hm.put(str, 2);
                    }
                    result = Math.max(result, hm.get(str) + samep);
                }
            }
            result = Math.max(result, samex);
        }
        return result;
    }

    private int gcd(int a, int b){
        if (a == 0) return b;

        return gcd(b % a, a);
    }
}