all combinations of four integers adding up to 100

100.rb

haystack = []
0.upto(100) do |i|
  0.upto(100) do |j|
    0.upto(100) do |k|
      0.upto(100) do |l|
        test = [i,j,k,l].sort
        unless haystack.include? test
          puts "#{test.join(', ')}\n" if test.inject(&:+) == 100
          haystack << test
        end
      end
    end
  end
end
puts "========"
puts haystack.size