Type Challenges Judge

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Join

提出詳細

type Join<T extends unknown[], U extends string | number, Acc extends string = ""> =
  T extends [infer Head extends string, ...infer Rest] ? Rest extends [] ? `${Acc}${Head}` : Join<Rest, U, `${Acc}${Head}${U}`> : never
提出日時2025-09-16 13:33:50
問題Join
ユーザーbalckowl
ステータスAccepted
テストケース
import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<Join<['a', 'p', 'p', 'l', 'e'], '-'>, 'a-p-p-l-e'>>,
  Expect<Equal<Join<['Hello', 'World'], ' '>, 'Hello World'>>,
  Expect<Equal<Join<['2', '2', '2'], 1>, '21212'>>,
  Expect<Equal<Join<['o'], 'u'>, 'o'>>,
]