quicksort

quicksort.rb

def quicksort(arr)
  return arr if arr.size <= 1
  pivot = arr.last
  f, l = 0, arr.size - 1
  loop do
    loop { break if arr[f].nil? || arr[f] > pivot; f += 1 }
    loop { break if arr[l].nil? || arr[l] < pivot; l -= 1 }
    break if l < f
    arr[f], arr[l] = arr[l], arr[f]
  end
  return [quicksort(arr[0..l]), pivot, quicksort(arr[f..arr.size-2])].flatten
end

require "rspec"
describe "quicksort" do
  it do
    arr = 1.upto(1000).map{|i| i}.shuffle
    arr.sort == quicksort(arr)
  end
end