Given an array, sort it in a wave form such that; a1 <= a2 >= a3 <= a4 => a5 <= a6

WaveSort.rb

class WaveSort
  def initialize(ary)
    @input_ary = ary
  end

  # OPTIMIZED, checking current value against the next/prev element
  def wave_sort_optimized
    ary_len = @input_ary.length
    (0...@input_ary.length).step(2) do |i|
      if (i > 0) && (@input_ary[i] > @input_ary[i-1])
        swap(i, i-1)
      end

      if (i < ary_len-1) && (@input_ary[i] > @input_ary[i+1])
        swap(i, i+1)
      end
    end
    @input_ary
  end

  # BRUTE FORCE - sort then swap
  def wave_sort
    @input_ary.sort!
    ary_len = @input_ary.length - 1

    (1...ary_len).step(2) do |i|
      swap(i, i+1, @input_ary)
    end
    @input_ary.compact
  end

  def swap(i, j, ary = @input_ary)
    ary[i], ary[j] = ary[j], ary[i]
  end
end

w = WaveSort.new([10,90,49,2,1,5,23])
e = WaveSort.new([1.25,2.0,2.2,4.20,3.15,5.00])
d = WaveSort.new([2,-1,4,3,-6,-3,5,4])

print "The array after performing a wave sort look like: \n"

print w.wave_sort_optimized
print "\n"

print e.wave_sort_optimized
print "\n"

print d.wave_sort_optimized
print "\n"