private void rangeNode(Node2d node, Stack<Point2D> stack, RectHV rect) {
if (node == null) return;
if (!node.rect.intersects(rect)) return;
if (rect.contains(node.p)) stack.push(node.p);
rangeNode(node.left, stack, rect);
rangeNode(node.right, stack, rect);
}
public Iterable<Point2D> range(
RectHV rect) { // all points in the set that are inside the rectangle
Stack<Point2D> stack = new Stack<Point2D>();
rangeNode(root, stack, rect);
return stack;
}