PWC 247 Task 2 complete

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diff --git a/challenge-247/bob-lied/perl/ch-2.pl b/challenge-247/bob-lied/perl/ch-2.pl
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+#!/usr/bin/env perl
+# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
+#=============================================================================
+# ch-2.pl Perl Weekly Challenge 247 Task 2 Most Frequent Letter Pair
+#=============================================================================
+# You are given a string S of lower case letters 'a'..'z'.
+# Write a script that finds the pair of consecutive letters in S that
+# appears most frequently. If there is more than one such pair, choose
+# the one that is the lexicographically first.
+# Example 1 Input: $s = 'abcdbca'
+#           Output: 'bc'  ('bc' appears twice in `$s`)
+# Example 2 Input: $s = 'cdeabeabfcdfabgcd'
+#           Output: 'ab'
+#=============================================================================
+# Copyright (c) 2023, Bob Lied
+#=============================================================================
+
+use v5.38;
+
+use builtin qw/true false/; no warnings "experimental::builtin";
+
+use Getopt::Long;
+my $Verbose = 0;
+my $DoTest  = 0;
+
+GetOptions("test" => \$DoTest, "verbose" => \$Verbose);
+exit(!runTest()) if $DoTest;
+
+sub mflp($s)
+{
+    my %freq;
+    $freq{$_}++ for map { substr($s, $_, 2) } 0 .. (length($s)-2);
+    return (sort { $freq{$b} <=> $freq{$a} || $a cmp $b } keys %freq)[0];
+}
+
+sub runTest
+{
+    use Test2::V0;
+
+    is( mflp("abcdbca"),           'bc', "Example 1");
+    is( mflp("cdeabeabfcdfabgcd"), 'ab', "Example 2");
+
+    done_testing;
+}