带你读《图解算法小抄》十四、排序（23）

function shellSort(arr) {
  const len = arr.length;
  let gap = Math.floor(len / 2);
  while (gap > 0) {
    for (let i = gap; i < len; i++) {
      const current = arr[i];
      let j = i;
      while (j >= gap && arr[j - gap] > current) {
        arr[j] = arr[j - gap];
        j -= gap;
      }
      arr[j] = current;
    }
    gap = Math.floor(gap / 2);
  }
  return arr;
}