MeanClassifier

class Point {
    double x;
    double y;
    String type;
    
    public Point() {      
    }
    
    public Point(Point other) {
      this(other.type, other.x, other.y);
    }
    
    public Point(String type, double x, double y) {
      this.type = type;
      this.x = x;
      this.y = y;
    }
}
    
public Set<Point> training(Set<Point> points) {
  Set<String, Integer> count = new HashSet<String, Integer>();
  Set<Point> result = new HashSet<Point>();
  
  for (Point point: points) {
    if (!count.contains(point.type)) {
      Point newPoint = new Point(point);
      result.put(point.type, newPoint);
      count.put(point.type, 1);
    } else {
      Point sumPoint = result.get(point.type);
      sumPoint.x += point.x;
      sumPoint.y += point.y;
      count.put(point.type, count.get(type) + 1);
    }
  }
  
  for (Point point: result) {
    point.x /= count.get(point.type);
    point.y /= count.get(point.type);
  }
  
  return result;
}

public String classify(Point point, Set<Point> meanPoints) {
  double distMin = Double.MAX_VALUE;
  final double THRESHOLD = 2000.0 * 2000.0;
  
  String result = "Outlier";
  for (Point mean: meanPoints) {
    final double distTmp = distSq(mean, point);
    if (distTmp < distMin && distTmp < THRESHOLD) {
      distMin = distTmp;
      result = mean.type;
    }
  }
  return result;
}
  
public double distSq(Point a, Point b) {
  return (a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y);
}