3 files changed, 159 insertions, 0 deletions
diff --git a/challenge-277/jo-37/blog.txt b/challenge-277/jo-37/blog.txt
new file mode 100644
index 0000000000..868e083858
--- /dev/null
+++ b/challenge-277/jo-37/blog.txt
@@ -0,0 +1 @@
+https://github.sommrey.de/the-bears-den/2024/07/12/ch-277.html
diff --git a/challenge-277/jo-37/perl/ch-1.pl b/challenge-277/jo-37/perl/ch-1.pl
new file mode 100755
index 0000000000..fdd4301f76
--- /dev/null
+++ b/challenge-277/jo-37/perl/ch-1.pl
@@ -0,0 +1,87 @@
+#!/usr/bin/perl -s
+
+use v5.24;
+use Test2::V0;
+
+our ($tests, $examples, $verbose);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [-verbose] [--] [W11,w12,... W21,W22,...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+-verbose
+    list common words instead of their count
+
+W11,W12,... W21,W22,...
+    comma separated lists of words
+
+EOS
+
+
+### Input and Output
+
+main: {
+    my @common = count_common(map [split /,/], @ARGV);
+    say $verbose ? "(@common)" : scalar @common;
+}
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2024/07/12/ch-277.html#task-1
+
+
+sub count_common {
+    my %words;
+    my $li = $#_;
+    for my $i (0 .. $li) {
+        $words{$_}[$i]++ for $_[$i]->@*;
+    }
+    no warnings 'uninitialized';
+
+    grep {$li + 1 == grep $_ == 1, $words{$_}->@[0..$li]} keys %words
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+        is scalar count_common(
+            ["Perl", "is", "my", "friend"],
+            ["Perl", "and", "Raku", "are", "friend"]
+        ), 2, 'example 1';
+
+        is scalar count_common(
+            ["Perl", "and", "Python", "are", "very", "similar"],
+            ["Python", "is", "top", "in", "guest", "languages"]
+        ), 1, 'example 2';
+
+        is scalar count_common(
+            ["Perl", "is", "imperative", "Lisp", "is", "functional"],
+            ["Crystal", "is", "similar", "to", "Ruby"]
+        ), 0, 'example 3';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        is [count_common(
+            [qw(one two two three four five)],
+            [qw(one two three three four six)],
+            [qw(one two three four four seven)]
+        )], ['one'], 'three arrays with one common word';
+	}
+
+    done_testing;
+    exit;
+}
diff --git a/challenge-277/jo-37/perl/ch-2.pl b/challenge-277/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..41d0ac2369
--- /dev/null
+++ b/challenge-277/jo-37/perl/ch-2.pl
@@ -0,0 +1,71 @@
+#!/usr/bin/perl -s
+
+use v5.24;
+use Test2::V0;
+use List::Util 'uniqint';
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [I...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+I...
+    list of integers
+
+EOS
+
+
+### Input and Output
+
+say strong_pairs(@ARGV);
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2024/07/12/ch-277.html#task-2
+
+
+sub strong_pairs {
+    my @ints = uniqint sort {$a <=> $b} @_;
+    my ($yi, $cnt) = (1, 0);
+    for my $xi (0 .. $#ints) {
+        my $x = $ints[$xi];
+        $yi++ while $yi < @ints && $ints[$yi] < 2 * $x;
+        $cnt += $yi - $xi - 1;
+    }
+
+    $cnt;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is strong_pairs(1, 2, 3, 4, 5), 4, 'example 1';
+        is strong_pairs(5, 7, 1, 7), 1, 'example  2';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        is strong_pairs(map 2**$_,     0 .. 9), 0, 'no strong pairs';
+        is strong_pairs(map 2**$_ + 1, 0 .. 9), 9, 'neighbors are strong pairs';
+        is strong_pairs(10 .. 19),             45, 'all pairs are strong';
+
+	}
+
+    done_testing;
+    exit;
+}