gistfile1.txt

require "benchmark"

def func_a(*arrays)
  enumerators = arrays.map {|a| (a.each + [Float::INFINITY]).each }
  output = Set.new
  until enumerators.all? { _1.peek.infinite? }
    output << enumerators.min {|a,b| a.peek <=> b.peek }.next
  end
  output
end

def func_b(*arrays)
  arrays.reduce(:+).sort.uniq
end

def func_bb(*arrays)
  arrays.reduce(:+).uniq
end

def func_c(*arrays)
  Set.new.merge(*arrays)
end

arrays = 3.times.map { Array.new(10_000) { rand(1_000) }}

Benchmark.bmbm do |x|
  x.report("func_a") { func_a(*arrays) }
  x.report("func_b") { func_b(*arrays) }
  x.report("func_bb") { func_bb(*arrays) }
  x.report("func_c") { func_c(*arrays) }
end

__END__
Rehearsal -------------------------------------------
func_a    0.014743   0.000486   0.015229 (  0.015439)
func_b    0.001939   0.000121   0.002060 (  0.002069)
func_bb   0.000421   0.000046   0.000467 (  0.000479)
func_c    0.001669   0.000023   0.001692 (  0.001699)
---------------------------------- total: 0.019448sec

              user     system      total        real
func_a    0.012642   0.000113   0.012755 (  0.012797)
func_b    0.001905   0.000114   0.002019 (  0.002026)
func_bb   0.000311   0.000062   0.000373 (  0.000372)
func_c    0.001587   0.000021   0.001608 (  0.001659)