Untitled

require 'benchmark'
require 'set'

a = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
h = {'a' => 1, 'b' => 1, 'c' => 1, 'd' => 1,
     'e' => 1, 'f' => 1, 'g' => 1}

s = Set.new(a)

Benchmark.bm do |x|
  x.report do
    1_000_000.times do
      a.include?('d')
    end
  end
  x.report do
    1_000_000.times do
      h['d']
    end
  end
  x.report do
    1_000_000.times do
      s.include?('d')
    end
  end

  #    user     system      total        real
  # 0.520000   0.000000   0.520000 (  0.521729)
  # 0.260000   0.000000   0.260000 (  0.258423)
  # 0.350000   0.000000   0.350000 (  0.352357)
end