const subsetsWithDup = (arr) => {
    // sorting makes sure we have the most unique vectors
    // i.e. [2,1,2] === [1,2,2] (same)
    arr = arr.sort();
    return helper(arr);
}

const helper = (arr, index = 0, slate = [], results = [], set = new Set()) => {
    results.push(slate);

    if (index === arr.length)
        return;

    for (let i = index; i < arr.length; i++) {
        if(i != index && arr[i] == arr[i-1])
            continue;
        helper(arr, i + 1, [...slate, arr[i]], results, set);
    }

    return results;
}