quick_sort.rb

#!/usr/bin/env ruby

class Array
  def quicksort
    return self if size <= 1
    pivot = self[self.size / 2]
puts "# -------------------------------------------------------------------------"
puts "pivot: #{pivot}"
puts "self: #{self}"
    i = 0
    j = self.size - 1
    loop do
      i += 1 until self[i].to_i >= pivot && i < self.size
      j -= 1 until self[j].to_i <= pivot && j >= 0
puts "i: #{i} => #{self[i].to_i}, j: #{j} => #{self[j].to_i}"
      break if i >= j
      self[i], self[j] = self[j], self[i]
      i += 1
      j -= 1
puts "self: #{self}"
    end

    left = begin
             self[0..self.index(pivot) - 1].quicksort if self.index(pivot) > 0
           end
    right = self[self.index(pivot)..-1].quicksort
    left.to_a.concat(right)
  end
end

puts "# ========================================================================="
a = (1..10).to_a.shuffle
p a
p a.quicksort