快速排序 #

function quickSort(arr) {
  if (arr.length < 2) {
    return arr;
  }

  const pivotIndex = Math.floor(arr.length / 2);
  const pivot = arr[pivotIndex];

  const left = [];
  const right = [];

  for (let i = 0; i < arr.length; i++) {
    if (i === pivotIndex) {
      continue;
    }

    if (arr[i] <= pivot) {
      left.push(arr[i]);
    } else {
      right.push(arr[i]);
    }
  }

  return [...quickSort(left), pivot, ...quickSort(right)];
}