Question

I have a little problem, I have 8 characters, for example “a b c d a e f g”, and a list of words, for example:
mom, dad, bad, fag, abac

How can I check if I can or cannot compose these words with the letters I have?
In my example, I can compose bad, abac and fag, but I cannot compose dad (I have not two D) and mom (I have not M or O).

I’m pretty sure it can be done using a RegEx but would be helpful even using some functions in Perl..
Thanks in advance guys! 🙂

Answer 1

This is done most simply by forming a regular expression from the word that is to be tested.

This sorts the list of available characters and forms a string by concatenating them. Then each candidate word is split into characters, sorted, and rejoined with the regex term .* as separator. So, for instance, abac will be converted to a.*a.*b.*c.

Then the validity of the word is determined by testing the string of available characters against the derived regex.

use strict;
use warnings;

my @chars = qw/ a b c d a e f g /;
my $chars = join '', sort @chars;

for my $word (qw/ mom dad bad fag abac /) {
  my $re = join '.*', sort $word =~ /./g;
  print "$word is ", $chars =~ /$re/ ? 'valid' : 'NOT valid', "\n";
}

output

mom is NOT valid
dad is NOT valid
bad is valid
fag is valid
abac is valid