From c0af731be7392e728b19091e40d69a183cf2db60 Mon Sep 17 00:00:00 2001
From: Guillermo Ramos
Date: Sun, 28 Apr 2019 13:36:15 +0200
Subject: 005#1 (functional)

---
 005/ch1.pl | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 005/ch1.pl

(limited to '005')

diff --git a/005/ch1.pl b/005/ch1.pl
new file mode 100644
index 0000000..1d020a6
--- /dev/null
+++ b/005/ch1.pl
@@ -0,0 +1,31 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+# Functional implementation (tail-recursive)
+sub anagrams {
+	sub iter {
+		my ($word, @acc) = @_;
+		if (length($word) == 0) {
+			return @acc;
+		} else {
+			my ($head, $tail) = $word =~ /^(.)(.*)$/;
+			@_ = $tail; # Next word will be the tail of the previous one
+			foreach my $anagram (@acc) {
+				for (my $i = 0; $i <= length($anagram); $i++) {
+					push(@_, $anagram);
+					substr($_[-1], $i, 0) = $head;
+				}
+			}
+			goto &iter;
+		}
+	}
+	iter($_[0], (""));
+}
+
+for (@ARGV) {
+	for (anagrams($_)) {
+		print $_, "\n";
+	}
+}
-- 
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