vector<int> quickSort(vector<int> arr) {
    vector<int> left, equal, right;
    for(int i = 0; i < arr.size(); i++){
        if(arr[i] < arr[0]) left.push_back(arr[i]);
        else if(arr[i] > arr[0]) right.push_back(arr[i]);
        else equal.push_back(arr[i]);
    }
    left.insert(left.end(), equal.begin(), equal.end());
    left.insert(left.end(), right.begin(), right.end());
    return left;
}

sub quickSort {
    my $arr = shift;
    return sort {$a <=> $b} @$arr; 
}

function quickSort(arr: number[]): number[] {
    // for resusable
    const split = (arr: number[]): [number[], number[], number, number[]] => {
        let pivot = arr[0]
        let lh = []
        let rh = []
        for (let i in arr) {
            if (arr[i] < pivot) lh.push(arr[i])
            if (arr[i] > pivot) rh.push(arr[i])
        }
        return [[...lh, pivot, ...rh], lh, pivot, rh]
    }

    return split(arr)[0]
}

public static List<Integer> quickSort(List<Integer> arr) {
  // Write your code here
  int pivot = arr.get(0);
  List<Integer> left = new ArrayList<>();
  List<Integer> right = new ArrayList<>();
  for (Integer i : arr) {
    if (i < pivot) {
      left.add(i);
    } else if (i > pivot) {
      right.add(i);
    }
  }
  left.add(pivot);
  left.addAll(right);
  return left;
}