重複する数字を表示（Rubyの場合）

number = Array.new
File.open("../data_a.txt","r"){|f|
  f.each{|line|
    (line.to_i != 0) && (number << line.to_i)
  }
}

number.sort!

1.upto(number.size-1){|i| (number[i-1] == number[i]) && (p number[i])}