- Added solution by "Athanasius".

2 files changed, 135 insertions, 0 deletions

diff --git a/challenge-002/athanasius/perl5/ch-1.pl b/challenge-002/athanasius/perl5/ch-1.pl
new file mode 100644
index 0000000000..f831efa8d8
--- /dev/null
+++ b/challenge-002/athanasius/perl5/ch-1.pl
@@ -0,0 +1,29 @@
+use strict;
+use warnings;
+
+while (my $n = <DATA>)
+{
+    chomp $n;
+
+    if ($n =~  / ^  \+?          \.  \d+  $ /x       ||
+        $n =~ s/ ^ (\+?) 0* (\d+ \.? \d*) $ /$1$2/x)
+    {
+        print "$n\n";
+    }
+    else
+    {
+        print "$n is not a positive number\n";
+    }
+}
+
+__DATA__
+00012345
++0678
+0000090.123
++00456.789
+0.123
+000.123
+0
+00
+.123
+-01
diff --git a/challenge-002/athanasius/perl5/ch-2.pl b/challenge-002/athanasius/perl5/ch-2.pl
new file mode 100644
index 0000000000..17e15af2f7
--- /dev/null
+++ b/challenge-002/athanasius/perl5/ch-2.pl
@@ -0,0 +1,106 @@
+use strict;
+use warnings;
+use Const::Fast;
+
+const my $ZERO   => ord('0');
+const my $NINE   => ord('9');
+const my $A      => ord('A');
+const my $Y      => ord('Y');
+const my @DIGITS => ('0' .. '9', 'A' .. 'Y');
+const my @POWERS => get_powers();
+
+while (my $n = <DATA>)
+{
+    chomp $n;
+    my $p = base35to10($n);
+    my $q = base10to35($p);
+    printf "%8s(35) = %11s(10) = %8s(35)\n", $n, $p, $q;
+}
+
+sub base35to10
+{
+    my ($base35) = @_;
+    my  $base10  = 0;
+    my  $power   = 1;
+
+    for my $digit (reverse split //, $base35)
+    {
+        $base10 += digit35to10($digit) * $power;
+        $power  *= 35;
+    }
+
+    return $base10;
+}
+
+sub base10to35
+{
+    my ($base10) = @_;
+
+    $base10 < $POWERS[-1] or die "Number $base10 too large, stopped";
+
+    my $index  = get_highest_index($base10);
+    my $base35 = '';
+
+    for my $i (reverse 0 .. $index)
+    {
+        my $digit = $DIGITS[ int($base10 / $POWERS[$i]) ];
+        $base35  .= $digit;
+        $base10  %= $POWERS[$i];
+    }
+
+    return $base35;
+}
+
+sub get_highest_index
+{
+    my ($base10) = @_;
+    my  $index   = $#POWERS;
+
+    for my $i (reverse 1 .. $#POWERS - 1)
+    {
+        last if $base10 >= $POWERS[$i];
+        $index = $i - 1;
+    }
+
+    return $index;
+}
+
+sub digit35to10
+{
+    my ($digit) = @_;
+    my  $ord    = ord($digit);
+
+    return  $digit          if $ord >= $ZERO && $ord <= $NINE;
+    return ($ord - $A + 10) if $ord >= $A    && $ord <= $Y;
+
+    die "Unknown base-35 digit '$digit', stopped";
+}
+
+sub get_powers
+{
+    my @powers;
+    my $power = 1;
+
+    for (1 .. 13)
+    {
+        push @powers, $power;
+        $power *= 35;
+    }
+
+    return @powers;
+}
+
+__DATA__
+10
+17
+35
+52
+A
+1A
+100
+ABC
+123
+36
+0
+13579BEH
+4