fn main {
  let dsu = @dsu.new(10)

  let _ = dsu.merge(1, 2)
  let _ = dsu.merge(3, 4)

  println(dsu.groups()) // [[0], [1, 2], [3, 4], [5], [6], [7], [8], [9]]
  println(dsu.same(1, 2)) // true
  println(dsu.same(3, 1)) // false
  println(dsu.leader(2)) // 1

  let root = dsu.merge(1, 3); // 1
  println(root); // 1
  println(dsu.size(root)) // 4
}