Rubyでのクイックソート

quick_sort.rb

def quicksort(seq)
  if seq.size == 0
    return seq
  end
  pivot = seq[0]
  right = Array.new
  left = Array.new
  for i in 1..seq.size-1
    if seq[i] <= pivot
      left.push(seq[i])
    else
      right.push(seq[i])
    end
  end
  
  left = quicksort(left)
  right = quicksort(right)
  return left + [pivot] + right
  end

arr = [1,53,36,77,22,100,4,20]
p(quicksort(arr))