CSCI 3333
Data Structures
Summer 2008
Homework #1 Possible Solution

The following is a possible solution in Perl:

use strict;
#
#   Homework #1, CSCI 3333, Summer 2008
#   by Bun Yue
#
#   See http://dcm.uhcl.edu/courses/csci3333/Summer2008/hw/h1.html for
#   problem specification.
#

#   Open dictionary file
my $dictionary = "words.txt";
open (DICT, "<$dictionary") || die "Can't open dictionary file $dictionary.\n";

#   Get input characters for checking words and store them in the character array @ch
@ARGV >= 1 || die "usage: h1.pl ch1 ch2 ...\n";
my @ch = @ARGV;

#   Check each array element to contain only one character each.
foreach (@ch) {
    die "Arguments must be single characters.\n" if (length $_ > 1);
}

my $result = "";
my $resultCount = 0;
my $word = "";

WORD_LOOP:
while ($word = <DICT>) {
   #   Check each word in the dictionary.
  
   #   Remove the last character if it is a blank.
   chomp $word;
   foreach (@ch) {
      #   For each input character, if it is not found in the word,
      #   skip the word by going to the next iteration of the
      #   External loop.
      next WORD_LOOP if $word !~ /$_/i;
   }
   #   $word contains all characters. Add it to the result.
   $resultCount++;
   $result .= "   $resultCount: $word\n";
}
close DICT;

if ($resultCount) {
   print "There are $resultCount words containing all supplied characters:\n$result\n";
}
else {
   print "There are no words containing all supplied characters.\n";
}
exit 0;

The code above contains documentation that is a little redundant. I include them so you may understand the Perl code better. A more plausible version:

use strict;
#
#   Homework #1, CSCI 3333, Summer 2008
#   by Bun Yue
#
#   See http://dcm.uhcl.edu/courses/csci3333/Summer2008/hw/h1.html for
#   problem specification.
#

#   Open dictionary file
my $dictionary = "words.txt";
open (DICT, "<$dictionary") || die "Can't open dictionary file $dictionary.\n";

@ARGV >= 1 || die "usage: h1.pl ch1 ch2 ...\n";
my @ch = @ARGV;
foreach (@ch) {
    die "Arguments must be single characters.\n" if (length $_ > 1);
}

my $result = "";
my $resultCount = 0;
my $word = "";

WORD_LOOP:
while ($word = <DICT>) {
   #   Check each word in the dictionary.

   chomp $word;
   foreach (@ch) {
      next WORD_LOOP if $word !~ /$_/i;
   }
   #   $word contains all characters. Add it to the result.
   $resultCount++;
   $result .= "   $resultCount: $word\n";
}
close DICT;

if ($resultCount) {
   print "There are $resultCount words containing all supplied characters:\n$result\n";
}
else {
   print "There are no words containing all supplied characters.\n";
}
exit 0;

I do not expect you to know Perl or to understand the code above. The points I would like to make are two-folds:

• Different programming languages have different strength. For small job like this, a flexible scripting language with rich built-in data structures like Perl can provide elegant solutions. It is important for computing and IT professional to have a tool box of languages.
• The solution uses various built-in data structures in Perl, including arrays and regular expressions. A solid foundation in data structures is key for constructing effective solutions.

Output for the test cases are:

>h1.pl a b c d e f
There are 3 words containing all supplied characters:
   1: barefaced
   2: boldface
   3: feedback


>h1.pl a e i o u q
There are 14 words containing all supplied characters:
   1: consequential
   2: equatorial
   3: equinoctial
   4: equitation
   5: equivocal
   6: equivocate
   7: grandiloquent
   8: inconsequential
   9: liquefaction
   10: quasiorder
   11: quasiperiodic
   12: questionnaire
   13: sequestration
   14: Sequoia


>h1.pl a b c d e f g
There are no words containing all supplied characters.

>h1.pl w x y
There are 3 words containing all supplied characters:
   1: expressway
   2: taxiway
   3: waxy

> h1.pl x y w
There are 3 words containing all supplied characters:
   1: expressway
   2: taxiway
   3: waxy 

Additional test cases:

>h1.pl d a t s r u c e
There are 3 words containing all supplied characters:
   1: disturbance
   2: transconductance
   3: transducer

>h1.pl q z
There are 10 words containing all supplied characters:
   1: quartz
   2: quartzite
   3: quetzal
   4: Quezon
   5: quiz
   6: quizzes
   7: quizzical
   8: squeeze
   9: Vasquez
   10: Velasquez

>h1.pl a s t r e g m
There are 12 words containing all supplied characters:
   1: bremsstrahlung
   2: ferromagnetism
   3: gastronome
   4: heterogamous
   5: magisterial
   6: magistrate
   7: manslaughter
   8: metallurgist
   9: ringmaster
   10: smattering
   11: spectrogram
   12: stratagem