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copied!<p>The basic algorithm would go like this:</p> <pre><code>shapes.tail.foldLeft(boundingBox(shapes.head)) { case (box, shape) if box contains shape => box case (box, shape) if shape contains box => shape case (box, shape) => boxBounding(box, shape) } </code></pre> <p>Now you have to write <code>contains</code> and <code>boxBounding</code>, which is a pure algorithms problem more than a language problem.</p> <p>If the shapes all had the same center, implementing <code>contains</code> would be easier. It would go like this:</p> <pre><code>abstract class Shape { def contains(s: Shape): Boolean } case class Rectangle(width: Int, height: Int) extends Shape { def contains(s: Shape): Boolean = s match { case Rectangle(w2, h2) => width >= w2 && height >= h2 case Location(x, y, s) => // not the same center case Circle(radius) => width >= radius && height >= radius case Group(shapes @ _*) => shapes.forall(this.contains(_)) } } case class Location(x: Int, y: Int, shape: Shape) extends Shape { def contains(s: Shape): Boolean = // not the same center } case class Circle(radius: Int) extends Shape { def contains(s: Shape): Boolean = s match { case Rectangle(width, height) => radius >= width && radius >= height case Location(x, y) => // not the same center case Circle(r2) => radius >= r2 case Group(shapes @ _*) => shapes.forall(this.contains(_)) } } case class Group(shapes: Shape*) extends Shape { def contains(s: Shape): Boolean = shapes.exists(_ contains s) } </code></pre> <p>As for <code>boxBounding</code>, which takes two shapes and combine them, it will usually be a rectangle, but can be a circle under certain circunstances. Anyway, it is pretty straight-forward, once you have the algorithm figured out.</p>

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