Sum of pairs in ruby

gistfile1.rb

def get_pairs(arr, sum)
  len = arr.length
  seen = Array.new(len, false)
  result = []

  for i in 0..len-1
    for j in i+1..len-1
      if arr[i] + arr[j] == sum && !seen[j] && !seen[i]
        seen[i], seen[j] = true, true
        result << [arr[i], arr[j]]
      end
    end
  end

  result
end

puts get_pairs([5, 5, 5, 0, 0, 0, 5], 5)
puts get_pairs([3, 3, 6, 0], 6)