Merge pull request #12933 from wlmb/challenges

Solve PWC345

3 files changed, 57 insertions, 0 deletions

diff --git a/challenge-345/wlmb/blog.txt b/challenge-345/wlmb/blog.txt
new file mode 100644
index 0000000000..11ee83e717
--- /dev/null
+++ b/challenge-345/wlmb/blog.txt
@@ -0,0 +1 @@
+https://wlmb.github.io/2025/10/27/PWC345/
diff --git a/challenge-345/wlmb/perl/ch-1.pl b/challenge-345/wlmb/perl/ch-1.pl
new file mode 100755
index 0000000000..7323bfcf84
--- /dev/null
+++ b/challenge-345/wlmb/perl/ch-1.pl
@@ -0,0 +1,27 @@
+#!/usr/bin/env perl
+# Perl weekly challenge 345
+# Task 1:  Peak Positions
+#
+# See https://wlmb.github.io/2025/10/27/PWC345/#task-1-peak-positions
+use v5.36;
+use feature qw(try);
+use PDL;
+use PDL::NiceSlice;
+
+die <<~"FIN" unless @ARGV;
+    Usage: $0 A0 A1...
+    to find the local maxima of the arrays An,
+    given by strings of the form
+    "[X0 X1...]" that may be parsed by PDL.
+    FIN
+for(@ARGV){
+    try {
+	my $ints=pdl($_);
+	# pad with smaller numbers at boundaries
+	my $padded=append(append($ints(0)-1, $ints), $ints(-1)-1);
+	my $indices=which(($padded>$padded->rotate(1))&($padded>$padded->rotate(-1)));
+	$indices -= 1; # remove left boundaries
+	say "$_ -> $indices";
+    }
+    catch($e){warn $e;}
+}
diff --git a/challenge-345/wlmb/perl/ch-2.pl b/challenge-345/wlmb/perl/ch-2.pl
new file mode 100755
index 0000000000..dbca6230af
--- /dev/null
+++ b/challenge-345/wlmb/perl/ch-2.pl
@@ -0,0 +1,29 @@
+#!/usr/bin/env perl
+# Perl weekly challenge 345
+# Task 2:  Last Visitor
+#
+# See https://wlmb.github.io/2025/10/27/PWC345/#task-2-last-visitor
+use v5.36;
+use feature qw(try);
+die <<~"FIN" unless @ARGV;
+    Usage: $0 A0 A1...
+    where An is a string with space separated numbers, positive
+    or -1. For each run of -1's output the previously seen positive
+    numbers, or -1 if they have been exhausted.
+    FIN
+for(@ARGV){
+    try {
+	my $count=0; # count of succesive -1's
+	my @answer = my @seen =();
+	my @input = split " ";
+	for(@input){
+	    unshift(@seen, $_), $count=0, next if $_ > 0;
+	    die "Only positive numbers and -1 are allowed: $_"
+		unless $_ == -1;
+	    push @answer, $count<@seen? $seen[$count]:-1;
+	    ++$count;
+	}
+	say "[$_] -> [@answer]";
+    }
+    catch($e){warn $e;}
+}