type Last<T extends any[]> = T extends [...any[], infer L] ? L : never;

Solution by asylbekduldiev #36405

type Last<T extends any[]> = T extends [...infer R, infer F] ? F : never;

Solution by AleksandrShcherbackov #36163

// your answers
type Last<T extends any[]> = T extends [...infer rest, infer last] ? last : never

Solution by lishenli1994 #36158

// 递归
type Last<T extends any[]> =
  T extends [infer First, ...infer Rest]
    ? Rest["length"] extends 0
    ? First
    : Last<Rest>
    : never;

Solution by qtycc-cc #35929

type Last<T extends any[]> = T['length'] extends 0 ? never : T extends [...any,infer U] ? U : 0;

Solution by tac-tac-go #35866

type Last<T extends any[]> = T extends [...infer _,infer Last] ? Last : never

Solution by EvilEl #35840

// 你的答案
// 基于Typescript 4.0.5
type Last<T extends any[]> = T extends [infer F, ...infer R]
  ? R["length"] extends 0
    ? F
    : [F, ...T][T["length"]]
  : never

Solution by a42195472 #35593

type Last<T extends any[]> = T extends [...any, infer L] ? L : never;

Solution by gangnamssal #35555

type Last<T extends any[]> = T extends [...infer A,infer U] ? U : never

Solution by TaueFenCheng #35534

type Last<T extends unknown[]> = T extends [...arg: unknown[], v:infer V] ? V : never

Solution by RanungPark #35481

// your answers
type arrOne = ["a", "b", "c"];
type arrTwo = [3, 2, 1];

type Last<T extends unknown[]> = T extends [...infer Pending, infer L] ? L : never;

const tail1: Last<arrOne> = "c";
const tail2: Last<arrTwo> = 1;

Solution by Sathiyapramod #35452

type Last<T extends any[]> = T extends [...infer Rest, infer Last] ? Last : never

Solution by eunsukimme #35122

type Last<T extends any[]> = T extends [...infer Rest, infer LastElement] ? LastElement : never

Solution by 2njeong #35081

// your answers

Solution by 2njeong #35080

type Last<T extends any[]> = T extends [...any[], infer L] ? L : never;

Solution by raeyoung-kim #35000

type Last<T extends any[]> = T extends [...any[], infer L] ? L : never;

Solution by 56aiden90 #34955

type Last<T extends any[]> = T extends [infer A, ...infer Rest] ? Rest extends [infer B, ...infer Rest2] ? Last : A : never;

我这个方法可能不是最好的，但是如果是type Last<T extends any[]> = T extends [...any, infer L] ? L : T这样的，在实际运行代码层面又是不合理的，type Last<T extends any[]> = [any, ...T][T["length"]];又不好理解，所以我还是采用最原始的做法。

Solution by shx123qwe #34916

type Last<T extends unknown[]> = T extends [infer Last]
  ? Last
  : T extends [infer _, ...infer Rest]
    ? Last<Rest>
    : never;

Solution by SayaOvO #34823

// your answers
type Last<T extends any[]> = T extends [...any, infer L] ? L : never;

Solution by zeyuanHong0 #34796

type Last<T extends any[]> = T extends [...any[], infer M] ? M : never;

Solution by nathan2slime #34656

type Last<T extends unknown[]> = [never, ...T][T["length"]];

// or 

type Last<T extends unknown[]> = T extends [... infer Head, infer Tail] ? Tail : never

Solution by binhdv155127 #34633

type Last<T extends any[]> = T['length'] extends 0 ? never : [any, ...T][T['length']]
// your answers

Solution by Rustamaha #34599

type Last<T extends any[]> = T['length'] extends 1
  ? T[0]
  : T extends [infer I, ...infer R] ? Last<R> : never
// your answers

Solution by Rustamaha #34598

type Last<T extends any[]> = T extends [...infer rest, infer F] ? F : never

Solution by Hailey0930 #34569

type Last<T extends any[]> = T extends [...infer B,infer C] ?  C : never

Solution by devshinthant #34565

// your answers
type Last<T extends any[]> = T extends [...infer F, infer L] ? L: never

Solution by gobielJonathan #34471

type Last<T extends any[]> = T extends [infer L, ...infer R] ? R['length'] extends 0 ? L : Last<R> : never

Solution by ktim816 #34435

type Last<T extends any[]> = T extends [infer A, ...infer Rest] 
  ? Rest['length'] extends 0 ? A : Last<Rest>
  : never

Solution by rookie-luochao #34386

// 你的答案

type Last<T extends any[]> = T extends [...infer A,infer B]?B:never

Solution by W-fitTiger #34255

문제설명

이 챌린지에는 TypeScript 4.0 사용이 권장됩니다.

배열 T를 사용하고 마지막 요소를 반환하는 제네릭 Last<T>를 구현합니다.

예시

type arr1 = ["a", "b", "c"];
type arr2 = [3, 2, 1];

type tail1 = Last<arr1>; // expected to be 'c'
type tail2 = Last<arr2>; // expected to be 1

풀이

type Last<T extends any[]> = T[T["length"] - 1];

처음에는 다음과 같은 방식으로 접근했습니다. 하지만 타입스크립트에서는 타입시스템이 정수 "연산"을 지원하지 않기 떄문에, T["length"]-1을 접근이 안되는 문제가 있었습니다. 따라서 다른 방법이 필요했습니다.

type Last<T extends any[]> = T extends [...infer Rest, infer Last]
	? Last
	: never;

solution

/* _____________ 여기에 코드 입력 _____________ */

type Last<T extends any[]> = T extends [...infer Rest, infer Last]
	? Last
	: never;

/* _____________ 테스트 케이스 _____________ */
import type { Equal, Expect } from "@type-challenges/utils";

type cases = [
	Expect<Equal<Last<[2]>, 2>>,
	Expect<Equal<Last<[3, 2, 1]>, 1>>,
	Expect<Equal<Last<[() => 123, { a: string }]>, { a: string }>>
];

Solution by adultlee #34155

00015-medium-last

문제설명

풀이

solution