biggest_product.rb

require 'benchmark'

# Solution 1
def solution_1(list_of_inputs)
  list_of_inputs
    .sort { |x, y| x<=>y }
    .first(3)
    .reduce(&:*)
end

# Solution 2
def solution_2(list_of_inputs)
  x, y, z = [0,0,0]
  a, b    = [0,0]

  list_of_inputs.each do |i|
    if i < a
      a, b = i, a
    elsif i > a and i < b
      b = i
    elsif i > x
      x, y, z = i, x, y
    elsif i < x and i > y
      y, z = i, y
    elsif i < y and i > z
      z = i
    end
  end

  a * b > x * y ? a * b * x : x * y * z
end

n = 50000
Benchmark.bm do |x|
  list = (-1_000..1_000).to_a.shuffle
  x.report("solution 2:") { n.times do solution_2(list) end }
  x.report("solution 1:") { n.times do solution_1(list) end }
end