快速排序quickSort

function quickSort(input) {
  if (input.length <= 1) return input
  var left = [], right = []
  for (var i = 1; i < input.length; i++) {
    input[i] < input[0] ? left.push(input[i]) : right.push(input[i])
  }
  return quickSort(left).concat(input[0], quickSort(right))
}