30430 - Tower of hanoi

[Sun79]

type Hanoi<N extends number, From = 'A', To = 'B', Intermediate = 'C'> = Helper<N, [], From, To, Intermediate>
type Helper<N extends number, C extends 1[], From extends unknown, To extends unknown, Intermediate extends unknown> = C['length'] extends N
  ? []
  : [...Helper<N, [...C, 1], From, Intermediate, To>, [From, To], ...Helper<N, [...C, 1], Intermediate, To, From>]

[lvjiaxuan]

crazy

[Grothendieck42]

Similar solution

type Hanoi<
  N extends number,
  From = "A",
  To = "B",
  Intermediate = "C",
  CurrentIndex extends 1[] = []
> = CurrentIndex["length"] extends N
  ? []
  : [
      ...Hanoi<N, From, Intermediate, To, [...CurrentIndex, 1]>,
      [From, To],
      ...Hanoi<N, Intermediate, To, From, [...CurrentIndex, 1]>
    ]