From d6966208224bb37ca532519a50849c686808582b Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Wed, 24 Oct 2012 23:18:13 -0500
Subject: forgot to commit these

---
 HAMM.pl |  8 ++++++++
 PERM.pl | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 HAMM.pl
 create mode 100644 PERM.pl

diff --git a/HAMM.pl b/HAMM.pl
new file mode 100644
index 0000000..0debb4a
--- /dev/null
+++ b/HAMM.pl
@@ -0,0 +1,8 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use 5.016;
+
+chomp(my $line1 = <>);
+chomp(my $line2 = <>);
+say length(($line1 ^ $line2) =~ s/\x00//gr);
diff --git a/PERM.pl b/PERM.pl
new file mode 100644
index 0000000..b9d2d10
--- /dev/null
+++ b/PERM.pl
@@ -0,0 +1,36 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use 5.016;
+
+sub factorial {
+    my ($n) = @_;
+    return 1 if $n < 2;
+    return $n * factorial($n - 1);
+}
+
+sub permutations {
+    my ($n) = @_;
+    my $string = join('', 1..$n);
+    return map { _permutation($string, $_) } 0..(factorial($n) - 1);
+}
+
+sub _permutation {
+    my ($string, $index) = @_;
+
+    return '' if $string eq '';
+
+    my $fact = factorial(length($string) - 1);
+
+    my $current_index = int($index / $fact);
+    my $rest          = $index % $fact;
+
+    my $first_digit = substr($string, $current_index, 1);
+    substr($string, $current_index, 1, '');
+
+    return $first_digit . _permutation($string, $rest);
+}
+
+my $n = <>;
+say factorial($n);
+say join(' ', split '') for permutations($n);
-- 
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