research-portable-memory/Swift/Memory.Aux.swift

func memory_generateConstPlayfield(
  _ n: Int
) -> [Int: Int] {
  var idGroups = [Int: Int]()
  var id = 0
  for gid in stride(from: 0, to: n, by: 1) {
    idGroups[id] = gid
    id += 1
    idGroups[id] = gid
    id += 1
  }

  return idGroups
}