Ruby と Perl で解くAtCoder ABC 161 D 幅優先探索 - Qiita

k = gets.chomp.to_i cnt = 0 que = [] (1..9).each do |i| que.push(i) cnt += 1 if cnt == k puts i exit end end while que.size > 0 do n = que.shift if n % 10 == 0 cnt += 1 if cnt == k puts n * 10 exit end que.push(n * 10) cnt += 1 if cnt == k puts n * 10 + 1 exit end que.push(n * 10 + 1) end if n % 10 != 0 && n % 10 != 9 cnt += 1 if cnt == k puts n * 10 + n % 10 - 1 exit end que.push(n * 10 + n % 10