From 8df97a656543017b5485276bdfef3961fa463486 Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Sun, 21 Oct 2012 11:04:18 -0500
Subject: another solution

---
 GRPH.pl | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 GRPH.pl

diff --git a/GRPH.pl b/GRPH.pl
new file mode 100644
index 0000000..65c351e
--- /dev/null
+++ b/GRPH.pl
@@ -0,0 +1,40 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use 5.016;
+
+my %dna;
+
+sub check_pair {
+    my ($name, $other) = @_;
+    return if $name eq $other;
+    if (substr($dna{$name}, 0, 3) eq substr($dna{$other}, -3)) {
+        say "$other $name";
+    }
+    if (substr($dna{$other}, 0, 3) eq substr($dna{$name}, -3)) {
+        say "$name $other";
+    }
+}
+
+my ($name, $dna);
+while (<>) {
+    chomp;
+    if (/^>(.*)/) {
+        my $new_name = $1;
+        if ($name) {
+            $dna{$name} = $dna;
+            for my $other (keys %dna) {
+                check_pair($name, $other);
+            }
+        }
+        $name = $new_name;
+        $dna = '';
+    }
+    else {
+        $dna .= $_;
+    }
+}
+$dna{$name} = $dna;
+for my $other (keys %dna) {
+    check_pair($name, $other);
+}
-- 
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