2020-01-28 插入排序

function insertionSort(arr) {
  const len = arr.length
  if (len <= 1) return arr

  for (i = 1; i < len; ++i) {
    let val = arr[i]
    let j = i - 1
    for (; j >= 0; --j) {
      if (arr[j] > val) {
        arr[j + 1] = arr[j]
      } else {
        break
      }
    }
    arr[j + 1] = val
  }
  return arr
}