8804 - 两数之和

[JhonLandy]

type Length<Num extends number, Len extends number[] = []>  = 
  Len['length'] extends Num 
    ? Len 
    : Length<Num, [...Len, 1]>;

type Sum<T extends any[], U extends any[]> = [...T, ...U]['length'];

type FindTarget<Num extends number, R extends number[], Target extends number> = 
  R extends [infer First extends number, ...infer Rest extends number[]]
    ? Sum<Length<Num>, Length<First>> extends Target 
      ? true
      : FindTarget<Num, Rest, Target> extends true 
        ? true
        : FindTarget<First, Rest, Target> 
    : false;

type TwoSum<T extends number[], U extends number> = T extends [infer First extends number,  ... infer Rest extends number[]]
  ? FindTarget<First, Rest, U> 
  : false