18/10/23 22:19:56.82 UJUp/CV/.net
>>172 Ruby
f=->n{n.to_s(26).tr('0-9a-p',r='@-Y').sub(/(.)@/){$1.tr('A-Z',r)+?Z}.delete ?@}
g=->s{s.tr('A-Z','0-9a-p').to_i(26)+(26**s.length-1)/25}
puts '%s => %s'%[$_.chop!,~/\d/?f[$_.to_i]:g[$_]]while gets
# =>
A => 1
AA => 27
ABC => 731
26 => Z
266379 => ODAI