type BitNum = [TNumOf<1>, TNumOf<2>, TNumOf<4>, TNumOf<8>, TNumOf<16>, TNumOf<32>, TNumOf<64>, TNumOf<128>];
type TNum = 0[];
type TNumOf<N extends number, _A extends 0[] = []> = _A["length"] extends N ? _A : TNumOf<N, [..._A, 0]>;
type AddTNum<A extends TNum, B extends TNum> = [...A, ...B];
type PlusOne<N extends number> = [...TNumOf<N>, 0]["length"] extends number ? [...TNumOf<N>, 0]["length"] : never;
type SplitStr<S extends string> = S extends `${infer L}${infer R}` ? [L, ...SplitStr<R>] : []
type Reverse<T extends unknown[], _Res extends unknown[] = []> =
  T extends [infer L, ...infer R]
  ? R extends unknown[] ? Reverse<R, [L, ..._Res]> : [L, ..._Res]
  : _Res

type BinaryToDecimal_Impl<S extends string[], _Digit extends number = 0, _Res extends TNum = []> =
  _Digit extends S["length"] ? _Res["length"]
  : S[_Digit] extends "1"
  ? BinaryToDecimal_Impl<S, PlusOne<_Digit>, AddTNum<_Res, BitNum[_Digit]>>
  : BinaryToDecimal_Impl<S, PlusOne<_Digit>, _Res>;

type BinaryToDecimal<S extends string> = BinaryToDecimal_Impl<Reverse<SplitStr<S>>>;

import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<BinaryToDecimal<'10'>, 2>>,
  Expect<Equal<BinaryToDecimal<'0011'>, 3>>,
  Expect<Equal<BinaryToDecimal<'00000000'>, 0>>,
  Expect<Equal<BinaryToDecimal<'11111111'>, 255>>,
  Expect<Equal<BinaryToDecimal<'10101010'>, 170>>,
]