Add solution for challenge 193.

Signed-off-by: Thomas Köhler <jean-luc@picard.franken.de>

3 files changed, 91 insertions, 0 deletions

diff --git a/challenge-193/jeanluc2020/README b/challenge-193/jeanluc2020/README
new file mode 100644
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+++ b/challenge-193/jeanluc2020/README
@@ -0,0 +1 @@
+Solution by Thomas Köhler
diff --git a/challenge-193/jeanluc2020/perl/ch-1.pl b/challenge-193/jeanluc2020/perl/ch-1.pl
new file mode 100755
index 0000000000..5e597c93ef
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+++ b/challenge-193/jeanluc2020/perl/ch-1.pl
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+#!/usr/bin/perl
+# task1.pl
+
+use warnings;
+use strict;
+
+my $input = $ARGV[0];
+$input //= 2;
+
+my $LENGTH = 0;
+my $MAX_WIDTH = 80;
+
+print_binaries("", $input);
+# Add a newline at the end, but "delete" the ", " and the end of the last string
+print " \n" if $input; # No need to print "\n" if $input is 0
+
+# we recursively create all possible binary numbers. Once hitting a leaf, we
+# print the current number and return to the caller
+# This way, we go recursively to a depth that's one more than the length we
+# provide as input (remaining length of 0 is used to indicate we reached a leaf)
+sub print_binaries {
+    my $current_string = shift;
+    my $remaining_digits = shift;
+    unless ($remaining_digits) {
+        # $remaining_digits is 0, so we can print what we have
+        # in $current_string and return.
+        # In case we're longer than $MAX_WIDTH, we print a "\n"
+        # first and then reset $LENGTH
+        $LENGTH += length("$current_string, ");
+        if ($LENGTH > $MAX_WIDTH) {
+            print "\n";
+            $LENGTH = length("$current_string, ");
+        }
+        print "$current_string, ";
+        return;
+    }
+    # We still have some remaining digits to go, so
+    # recursively walk down for each possible digit
+    foreach my $digit ( 0..1 ) {
+        print_binaries("$current_string$digit", $remaining_digits-1);
+    }
+}
diff --git a/challenge-193/jeanluc2020/perl/ch-2.pl b/challenge-193/jeanluc2020/perl/ch-2.pl
new file mode 100755
index 0000000000..abfc52b42c
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+++ b/challenge-193/jeanluc2020/perl/ch-2.pl
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+#!/usr/bin/perl
+# task2.pl
+#
+
+use warnings;
+use strict;
+use Data::Dumper;
+use FindBin qw($Bin);
+use lib "$Bin/lib";
+
+my @s = ("adc", "wzy", "abc");
+find_odd(@s);
+@s = ("aaa", "bob", "ccc", "ddd");
+find_odd(@s);
+
+# Given an array of strings, let's find the odd one
+sub find_odd {
+    my @s = @_;
+    my $len = length($s[0]);
+    my $result;
+    foreach my $string (@s) {
+        # Just making sure all input strings share the same length
+        die "Not all strings are of the same length!\n" if length($string) != $len;
+        my @chars = split //,$string;
+        my @diffs = ();
+        # As long as we have at least two characters left, remove the first and
+        # calculate the difference of the second and the first
+        # Push the result onto another array
+        while(scalar(@chars) > 1) {
+            my $c = shift @chars;
+            # Yes, ord() is shifted by 97 as opposed to 0->a, ..., but since
+            # this affects both parts of the difference, that amounts to
+            # zero difference.
+            push @diffs, (ord($chars[0]) - ord($c));
+        }
+        # Build a hash key from the diffs and push the original string
+        # onto an array which is in the result hash for the calculated key
+        # This way the odd string will be the only string in its array,
+        # while the other strings share they key, filling up the corresponding
+        # array with multiple values
+        my $key = join(",", @diffs);
+        push @{$result->{$key}}, $string;
+    }
+    foreach my $k (keys %$result) {
+        # The array with only one element contains the odd string
+        print "Odd string $result->{$k}->[0]!\n" if scalar(@{$result->{$k}}) == 1;
+    }
+}