2020-01-28 快速排序（原地排序）

function swap(arr, i, j) {
  const temp = arr[i]
  arr[i] = arr[j]
  arr[j] = temp
}

function partition(arr, pIndex, left, right) {
  const p = arr[pIndex]
  let startIndex = left
  for (let i = left; i < right; i++) {
    if (arr[i] < p) {
      swap(arr, i, startIndex)
      startIndex++
    }
  }
  swap(arr, startIndex, pIndex)

  return startIndex
}

function quick_sort_c(arr, left, right) {
  if (left < right) {
    let pIndex = right
    let partitionIndex = partition(arr, pIndex, left, right)
    quick_sort_c(arr, left, partitionIndex - 1 < left ? left : partitionIndex - 1)
    quick_sort_c(arr, partitionIndex + 1 > right ? right : partitionIndex + 1, right)
  }

}

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

  return quick_sort_c(arr, 0, len - 1)
}