The function patition for quickSort can't support array which has duplicates.

[SikyChen]

It is a good way to patition a deduplicated array , but if the unsorted array is [1,2,3,4,4,4,2,4,4,6,7], the function can't move 2 to front.

I'd like to write a patition function like this:

function partition(array, left, right, compareFn) {
  const pivot = array[Math.floor((right + left) / 2)];
  let l = left;
  let r = right;
  let i = left;

  while (i <= r) {
    if (compareFn(array[i], pivot) === Compare.LESS_THAN) {
      swap(array, i, l);
      i++;
      l++;
    }
    else if (compareFn(array[i], pivot) === Compare.BIGGER_THAN) {
      swap(arr, i, r);
      r--;
    }
    else {
      i++;
    }
  }

  // return [l, r];
  return l;
}

PS：I learned a lot from your book, thank you~