gistfile1.rb

def no_repeats(year_start, year_end)
  no_repeats=[]
  (year_start..year_end).each do |yr|
    no_repeats<<yr if no_repeat?(yr)
  end
  no_repeats
end

def no_repeat?(year)
  num_seen=[]
  year.to_s.each_char do |num|
    if num_seen.include?(num)
      return false
    else
      num_seen<<num
    end
  end
  return true
end

puts no_repeats(1980,1990);