- Added solutions by Lubos Kolouch.

2 files changed, 233 insertions, 0 deletions

diff --git a/challenge-015/lubos-kolouch/perl5/ch-1.pl b/challenge-015/lubos-kolouch/perl5/ch-1.pl
new file mode 100644
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+++ b/challenge-015/lubos-kolouch/perl5/ch-1.pl
@@ -0,0 +1,91 @@
+#!/usr/bin/perl 
+#===============================================================================
+#
+#         FILE: 2019_15_1.pl
+#
+#        USAGE: ./2019_15_1.pl
+#
+#  DESCRIPTION: Perl Weekly challenge w15 #1
+#               Write a script to generate first 10 strong and weak prime numbers.
+#
+#      OPTIONS: ---
+# REQUIREMENTS: ---
+#         BUGS: ---
+#        NOTES: ---
+#       AUTHOR: Lubos Kolouch
+# ORGANIZATION:
+#      VERSION: 1.0
+#      CREATED: 07/02/2019 09:47:38 PM
+#     REVISION: ---
+#===============================================================================
+
+use warnings;
+use strict;
+use feature qw{ say };
+
+my @strong_primes;
+my @weak_primes;
+
+# let's remember the previous and the next primes
+# it's not necessary to remember all of them
+
+my $last_prime =2;
+my $current_prime;
+my $next_prime;
+
+# simple prime check
+sub is_prime {
+    my $candidate = shift;
+
+    for my $n ( 2 .. int( sqrt($candidate) ) ) {
+
+        # if can be divided, no luck...
+        return 0 if ( $candidate % $n == 0 );
+    }
+
+    #cool, a prime!
+    return 1;
+}
+
+my $n = 2;
+while (1)
+{
+    $n++;
+
+    next unless is_prime($n);
+
+    # first run is like:
+    # last - 2 current - ? next - ?
+
+    unless ($current_prime) {
+        $current_prime = $n;
+        next;
+    }
+
+    # next runs are like :
+    # last - 2 current - 3 next - ?
+    # we need last - 2 current - 3 next - 5
+    # let's assign next prime and test the current one
+    $next_prime = $n;
+
+    push @strong_primes, $current_prime if $current_prime > ($last_prime + $next_prime)/2 and scalar @strong_primes < 10;
+    push @weak_primes, $current_prime if $current_prime < ($last_prime + $next_prime)/2 and scalar @weak_primes < 10;
+
+    # ok now let's shift to
+    # last - 3 current - 5
+    $last_prime = $current_prime;
+    $current_prime = $n;
+
+    last if (scalar @strong_primes > 9) and (scalar @weak_primes > 9);
+}
+
+say 'Strong primes: '. join ',', @strong_primes;
+say 'Weak primes: '. join ',', @weak_primes;
+
+
+use Test::More;
+
+is( is_prime(5), 1, 'test if prime 1' );
+is( is_prime(4), 0, 'test if prime 4');
+
+done_testing();
diff --git a/challenge-015/lubos-kolouch/perl5/ch-2.pl b/challenge-015/lubos-kolouch/perl5/ch-2.pl
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+++ b/challenge-015/lubos-kolouch/perl5/ch-2.pl
@@ -0,0 +1,142 @@
+#!/usr/bin/perl 
+#===============================================================================
+#
+#         FILE: 2019_15_2.pl
+#
+#        USAGE: ./2019_15_2.pl
+#
+#  DESCRIPTION: Perl Weekly challenge w15 #2
+#  Write a script to implement Vigenère cipher. The script should be able
+#  decode and encode. Checkout wiki page for more information.
+#
+#      OPTIONS: ---
+# REQUIREMENTS: ---
+#         BUGS: ---
+#        NOTES: ---
+#       AUTHOR: Lubos Kolouch
+# ORGANIZATION:
+#      VERSION: 1.0
+#      CREATED: 07/02/2019 09:47:38 PM
+#     REVISION: ---
+#===============================================================================
+
+use warnings;
+use strict;
+use feature qw{ say };
+
+sub encode_letter {
+    my ($plain, $key) = @_;
+
+    # calculate the shift for plain text
+    my $shift_plain = ord($plain) - ord('A');
+
+    # calculate the shift for key
+    my $shift_key = ord($key) - ord('A');
+
+    # calculate the resulting ASCII value
+    my $result =  ord('A') + ($shift_plain  +  $shift_key) % (ord('Z')-ord('A')+1);
+
+    return chr($result);
+}
+
+sub decode_letter {
+    my ($key, $cypher) = @_;
+
+    # calculate the shift for key
+    my $shift_key = ord($key) - ord('A');
+
+    # calculate the shift for cypher text
+    my $shift_cypher = ord($cypher) - ord('A');
+
+    # calculate the resulting ASCII value
+    my $result =  ord('A') + ($shift_cypher  -  $shift_key) % (ord('Z')-ord('A')+1);
+
+    return chr($result);
+}
+
+
+sub  encode_text {
+    my $text = shift;
+    my $key = shift;
+
+    # convert the text to arrays for convenience, could be also done as string
+    # with length
+
+    my @text_a = split //, $text;
+    my @key_a = split //, $key;
+
+    my $result;
+
+    for (0.. scalar @text_a -1) {
+        my $letter = $text_a[$_];
+
+        # encode each letter
+        $result .= encode_letter($letter, $key_a[$_ % scalar @key_a]);
+    }
+
+    return $result;
+
+}
+
+sub  decode_text {
+    my $text = shift;
+    my $key = shift;
+
+    # convert the text to arrays for convenience, could be also done as string
+    # with length
+
+    my @text_a = split //, $text;
+    my @key_a = split //, $key;
+
+    my $result;
+
+    for (0.. scalar @text_a -1) {
+        my $letter = $text_a[$_];
+
+        # decode each letter
+        $result .= decode_letter($key_a[$_ % scalar @key_a], $letter);
+    }
+
+    return $result;
+
+}
+
+# ------ MAIN STARTS HERE --------
+my ($text, $key, $direction) = @ARGV;
+
+die 'No text passed. Usage: script TEXT KEY DIRECTION("d" or "e")' unless $text;
+die 'No key passed. Usage: script TEXT KEY DIRECTION("d" or "e")' unless $key;
+die 'No direction passed. Usage: script TEXT KEY DIRECTION("d" or "e")' unless $direction;
+
+$text = uc($text);
+$key=uc($key);
+$direction = uc($direction);
+
+die 'direction must be d or e' unless $direction eq 'D' or $direction eq  'E';
+
+say encode_text($text, $key) if ($direction eq 'E');
+say decode_text($text, $key) if ($direction eq 'D');
+
+# ----------- TESTS ----------
+use Test::More;
+
+is( encode_letter('A','A'),'A', 'test encode A-A' );
+is( encode_letter('A','S'),'S', 'test encode A-S' );
+is( encode_letter('C','C'),'E', 'test encode C-C' );
+is( encode_letter('F','M'),'R', 'test encode F-M' );
+is( encode_letter('O','Y'),'M', 'test encode O-Y' );
+is( encode_letter('Y','L'),'J', 'test encode Y-L' );
+is( encode_letter('Z','Z'),'Y', 'test encode Z-Z' );
+
+is( decode_letter('A','A'),'A', 'test decode A-A' );
+is( decode_letter('A','S'),'S', 'test decode A-S' );
+is( decode_letter('C','C'),'A', 'test decode C-C' );
+is( decode_letter('F','M'),'H', 'test decode F-M' );
+is( decode_letter('O','Y'),'K', 'test decode O-Y' );
+is( decode_letter('Y','L'),'N', 'test decode Y-L' );
+is( decode_letter('Z','Z'),'A', 'test decode Z-Z' );
+is( encode_text('ATTACKATDAWN', 'LEMON'), 'LXFOPVEFRNHR', 'Test encode ATTACKATDAWN LEMON');
+is( decode_text('LXFOPVEFRNHR', 'LEMON'), 'ATTACKATDAWN', 'Test decode ATTACKATDAWN LEMON');
+isnt( decode_text('LXFOPVEFRNHR', 'LEMON'), 'DTTACKATDAWN', 'Test decode ATTACKATDAWN LEMON');
+isnt( encode_text('ATTACKATDAWN', 'LEMON'), 'OXFOPVEFRNHR', 'Test encode ATTACKATDAWN LEMON');
+done_testing();