Week 306 solutions

3 files changed, 168 insertions, 3 deletions

diff --git a/challenge-306/bob-lied/README b/challenge-306/bob-lied/README
index 77992b92ee..3a6c40ed45 100644
--- a/challenge-306/bob-lied/README
+++ b/challenge-306/bob-lied/README
@@ -1,4 +1,4 @@
-Solutions to weekly challenge 305 by Bob Lied
+Solutions to weekly challenge 306 by Bob Lied
 
-https://perlweeklychallenge.org/blog/perl-weekly-challenge-305/
-https://github.com/boblied/perlweeklychallenge-club/tree/master/challenge-305/bob-lied
+https://perlweeklychallenge.org/blog/perl-weekly-challenge-306/
+https://github.com/boblied/perlweeklychallenge-club/tree/master/challenge-306/bob-lied
diff --git a/challenge-306/bob-lied/perl/ch-1.pl b/challenge-306/bob-lied/perl/ch-1.pl
new file mode 100644
index 0000000000..e00b286920
--- /dev/null
+++ b/challenge-306/bob-lied/perl/ch-1.pl
@@ -0,0 +1,87 @@
+#!/usr/bin/env perl
+# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
+#=============================================================================
+# Copyright (c) 2025, Bob Lied
+#=============================================================================
+# ch-1.pl Perl Weekly Challenge 306 Task 1 Odd Sum
+#=============================================================================
+# You are given an array of positive integers, @ints.
+# Write a script to return the sum of all possible odd-length subarrays of
+# the given array. A subarray is a contiguous subsequence of the array.
+# Example 1 Input: @ints = (2, 5, 3, 6, 4)
+#           Output: 77
+#   Odd length sub-arrays:
+#   (2) => 2 (5) => 5 (3) => 3 (6) => 6 (4) => 4
+#   (2, 5, 3) => 10 (5, 3, 6) => 14 (3, 6, 4) => 13
+#   (2, 5, 3, 6, 4) => 20
+#   Sum => (2 + 5 + 3 + 6 + 4) + (10 + 14 + 13) + 20 => 77
+#
+# Example 2 Input: @ints = (1, 3)
+#           Output: 4
+#=============================================================================
+
+use v5.40;
+
+use List::Util qw/sum0/;
+
+use Getopt::Long;
+my $Verbose = false;
+my $DoTest  = false;
+
+GetOptions("test" => \$DoTest, "verbose" => \$Verbose);
+my $logger;
+{
+    use Log::Log4perl qw(:easy);
+    Log::Log4perl->easy_init({ level => ($Verbose ? $DEBUG : $INFO ),
+            layout => "%d{HH:mm:ss.SSS} %p{1} %m%n" });
+    $logger = Log::Log4perl->get_logger();
+}
+#=============================================================================
+
+exit(!runTest()) if $DoTest;
+
+say oddSum(@ARGV);
+
+#=============================================================================
+# This implements the operations literally, but loops repeatedly over
+# sub-arrays. It is possible to figure out how many times each element
+# appears in the sum as a function of its position and the length of the
+# array, which will be much more efficient.
+sub oddSum(@ints)
+{
+    my $sum = sum0 @ints;
+    for my $group ( map { 1 + 2*$_ } 1 .. int((@ints-1)/2) )
+    {
+        $logger->debug("group=$group");
+        for (my $i = 0; $i <= @ints-$group; $i++ )
+        {
+            $sum += $ints[$_] for ( $i .. ($i + $group - 1) );
+        }
+    }
+    return $sum;
+}
+
+# The number of times each element appears forms a pattern similar to
+# Pascal's triangle:
+
+# array  #  Position under sliding window X times
+# length #
+#  2     #  1  1
+#  3     #  2  2  2
+#  4     #  2  3  3  2
+#  5     #  3  4  5  4  3
+#  6     #  3  5  6  6  5  3
+#  7     #  4  6  8  8  8  7  4
+#  8     #  4  7  9 10 10  9  7  4
+#  9     #  5  8 11 12 13 12 11  8  5
+# 10     #  5  9 12 14 15 15 14 12  9  5
+
+sub runTest
+{
+    use Test2::V0;
+
+    is( oddSum(2,5,3,6,4), 77, "Example 1");
+    is( oddSum(1,3      ),  4, "Example 2");
+
+    done_testing;
+}
diff --git a/challenge-306/bob-lied/perl/ch-2.pl b/challenge-306/bob-lied/perl/ch-2.pl
new file mode 100644
index 0000000000..3edcf03f4f
--- /dev/null
+++ b/challenge-306/bob-lied/perl/ch-2.pl
@@ -0,0 +1,78 @@
+#!/usr/bin/env perl
+# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
+#=============================================================================
+# Copyright (c) 2025, Bob Lied
+#=============================================================================
+# ch-2.pl Perl Weekly Challenge 306 Task 2 Last Element
+#=============================================================================
+# You are given a array of integers, @ints.
+# Write a script to play a game where you pick two biggest integers in
+# the given array, say x and y. Then do the following:
+# a) if x == y then remove both from the given array
+# b) if x != y then remove x and replace y with (y - x)
+# At the end of the game, there is at most one element left.
+# Return the last element if found otherwise return 0.
+# Example 1 Input: @ints = (3, 8, 5, 2, 9, 2)
+#           Output: 1
+#   Step 1: pick 8 and 9 => (3, 5, 2, 1, 2)
+#   Step 2: pick 3 and 5 => (2, 2, 1, 2)
+#   Step 3: pick 2 and 1 => (1, 2, 2)
+#   Step 4: pick 2 and 1 => (1, 2)
+#   Step 5: pick 1 and 2 => (1)
+#
+# Example 2 Input: @ints = (3, 2, 5)
+#           Output: 0
+#   Step 1: pick 3 and 5 => (2, 2)
+#   Step 2: pick 2 and 2 => ()
+#=============================================================================
+
+use v5.40;
+
+use Getopt::Long;
+my $Verbose = false;
+my $DoTest  = false;
+
+GetOptions("test" => \$DoTest, "verbose" => \$Verbose);
+my $logger;
+{
+    use Log::Log4perl qw(:easy);
+    Log::Log4perl->easy_init({ level => ($Verbose ? $DEBUG : $INFO ),
+            layout => "%d{HH:mm:ss.SSS} %p{1} %m%n" });
+    $logger = Log::Log4perl->get_logger();
+}
+#=============================================================================
+
+exit(!runTest()) if $DoTest;
+
+say lastElem(@ARGV);
+
+#=============================================================================
+sub lastElem(@ints)
+{
+    @ints = sort { $b <=> $a } @ints;
+    while ( @ints > 1 )
+    {
+        if ( $ints[0] == $ints[1] )
+        {
+            shift @ints; shift @ints;
+            next;
+        }
+        else
+        {
+            $ints[1] = $ints[0] - $ints[1];
+            shift @ints;
+            @ints = sort { $b <=> $a } @ints;
+        }
+    }
+    return scalar(@ints);
+}
+
+sub runTest
+{
+    use Test2::V0;
+
+    is( lastElem(3,8,5,2,9,2), 1, "Example 1");
+    is( lastElem(3,2,5), 0, "Example 2");
+
+    done_testing;
+}