12345678910111213
export default function checkIfExist(arr: number[]): boolean {    const set = new Set<number>();
    for (let i = 0; i < arr.length; i++) {        if (set.has(arr[i] * 2) || (arr[i] % 2 === 0 && set.has(arr[i] / 2))) {            return true;        }        set.add(arr[i]);    }
    return false;}