10.pl

   1 #!/usr/bin/perl -w
   2
   3 use strict;
   4
   5 my @seats;
   6 while (<>) {
   7         chomp;
   8         y/FBRL/0110/;
   9         my $seat =  eval "0b$_";
  10         $seats[$seat] = 1;
  11 }
  12
  13 for (1 .. $#seats-1) {
  14         print $_, "\n" if $seats[$_-1] && $seats[$_+1]
  15                 && !$seats[$_];
  16 }