public static Point[] convexHull(Point[] points) {

Arrays.sort(points, Comparator.<Point>comparingInt(p -> p.x).thenComparingInt(p -> p.y));

int n = points.length;

Point[] hull = new Point[n + 1];

int cnt = 0;

for (int i = 0; i < 2 * n - 1; i++) {

int j = i < n ? i : 2 * n - 2 - i;

while (cnt >= 2 && isNotRightTurn(hull[cnt - 2], hull[cnt - 1], points[j])) --cnt;

hull[cnt++] = points[j];

}

return Arrays.copyOf(hull, cnt - 1);

}

static boolean isNotRightTurn(Point a, Point b, Point c) {

long cross = (long) (a.x - b.x) * (c.y - b.y) - (long) (a.y - b.y) * (c.x - b.x);

long dot = (long) (a.x - b.x) * (c.x - b.x) + (long) (a.y - b.y) * (c.y - b.y);

return cross < 0 || cross == 0 && dot <= 0;

}

public static class Point {

public final int x, y;

public Point(int x, int y) {

this.x = x;

this.y = y;

}

@Override

public String toString() {

return "Point{"

+ "x=" + x + ", y=" + y + '}';

}

}

// Usage example

public static void main(String[] args) {

Point[] points = {new Point(0, 0), new Point(0, 1), new Point(1, 0), new Point(0, 0)};

Point[] convexHull = convexHull(points);

System.out.println(Arrays.toString(convexHull));

}