type-challenges-judge

Type Challenges Judge

Problems

Progress

IndexOf

提出詳細

type Check<T, U> = T extends U ? U extends T ? true : false : false
type IndexOf<T extends readonly unknown[], U, K extends readonly unknown[] = []> =
  T extends [infer Head, ...infer Rest] ? Check<Head, U> extends true ? K["length"] : IndexOf<Rest, U, [...K, unknown]> : -1

提出日時	2025-09-16 13:02:34
問題	IndexOf
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<IndexOf<[1, 2, 3], 2>, 1>>,
  Expect<Equal<IndexOf<[2, 6, 3, 8, 4, 1, 7, 3, 9], 3>, 2>>,
  Expect<Equal<IndexOf<[0, 0, 0], 2>, -1>>,
  Expect<Equal<IndexOf<[string, 1, number, 'a'], number>, 2>>,
  Expect<Equal<IndexOf<[string, 1, number, 'a', any], any>, 4>>,
]