Quicksort

qsort.js

const swap = (items, first, second) => {
  const tmp = items[first];
  items[first] = items[second];
  items[second] = tmp;
};

const partition = (items, left, right) => {
  const pivot = items[Math.trunc((right + left) / 2)];

  while (left <= right) {
    while (items[left] < pivot) left++;
    while (items[right] > pivot) right--;
    if (left <= right) {
      swap(items, left, right);
      left++;
      right--;
    }
  }

  return left;
};

export const qsort = (items) => {
  if (items.length < 2) return;

  const go = (items, left, right) => {
    if (left >= right) return;
    const mid = partition(items, left, right);
    go(items, left, mid - 1);
    go(items, mid, right);
  };

  go(items, 0, items.length - 1);
};