From a8609bdf63cf6d5f0780c676b5cf4d48ecd72cbb Mon Sep 17 00:00:00 2001
From: Luis Mochan <mochan@fis.unam.mx>
Date: Mon, 21 Jul 2025 08:15:29 -0600
Subject: Solve PWC331

---
 challenge-331/wlmb/blog.txt     |  1 +
 challenge-331/wlmb/perl/ch-1.pl | 17 +++++++++++++++++
 challenge-331/wlmb/perl/ch-2.pl | 27 +++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)
 create mode 100644 challenge-331/wlmb/blog.txt
 create mode 100755 challenge-331/wlmb/perl/ch-1.pl
 create mode 100755 challenge-331/wlmb/perl/ch-2.pl

diff --git a/challenge-331/wlmb/blog.txt b/challenge-331/wlmb/blog.txt
new file mode 100644
index 0000000000..837eeaee1c
--- /dev/null
+++ b/challenge-331/wlmb/blog.txt
@@ -0,0 +1 @@
+https://wlmb.github.io/2025/07/21/PWC331/
diff --git a/challenge-331/wlmb/perl/ch-1.pl b/challenge-331/wlmb/perl/ch-1.pl
new file mode 100755
index 0000000000..f49164cec9
--- /dev/null
+++ b/challenge-331/wlmb/perl/ch-1.pl
@@ -0,0 +1,17 @@
+#!/usr/bin/env perl
+# Perl weekly challenge 331
+# Task 1:  Last Word
+#
+# See https://wlmb.github.io/2025/07/21/PWC331/#task-1-last-word
+use v5.36;
+die <<~"FIN" unless @ARGV;
+    Usage: $0 S1 S2...
+    to find the length of the last word of the strings Sn
+    FIN
+for(@ARGV){
+    say "$_ -> ",        # print the result
+	length           # compute the length
+	[split " "]      # separate into words
+	->[-1]           # choose last word
+	=~s/\W//gr       # remove non-word characters
+}
diff --git a/challenge-331/wlmb/perl/ch-2.pl b/challenge-331/wlmb/perl/ch-2.pl
new file mode 100755
index 0000000000..51f3e6f145
--- /dev/null
+++ b/challenge-331/wlmb/perl/ch-2.pl
@@ -0,0 +1,27 @@
+#!/usr/bin/env perl
+# Perl weekly challenge 331
+# Task 2:  Buddy Strings
+#
+# See https://wlmb.github.io/2025/07/21/PWC331/#task-2-buddy-strings
+use v5.36;
+die <<~"FIN" unless @ARGV && @ARGV%2==0;
+    Usage: $0 S1 T1 S2 T2...
+    to find if target string Tn may be obtained from the source string Sn
+    by a single permutation of two characters.
+    FIN
+for my($source, $target)(@ARGV){
+    say"$source $target -> ",
+	(my $joined="$source$;$target")        # join source and target using special character
+	=~                                     # match to
+	/^                                     # start of source
+        (.*)                                   # arbitrary string (group 1)
+        (.)                                    # a single character to permute (group 2)
+        (.*)                                   # arbitrary string (group 3)
+        (.)                                    # second character to permute (group 4)
+        (.*)                                   # arbitrary string (group 5)
+        $;                                     # end of source
+        \1\4\3\2\5                             # target is source with \2 and \4 permuted
+        $                                      # end of target
+        /x
+	?"True":"False";
+}
-- 
cgit