DAJ 318 blogged

3 files changed, 92 insertions, 0 deletions

diff --git a/blog.txt b/blog.txt
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+++ b/blog.txt
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+https://jacoby-lpwk.onrender.com/2025/04/24/your-embrace-and-my-collapse-weekly-challenge-318.html
diff --git a/challenge-318/dave-jacoby/perl/ch-1.pl b/challenge-318/dave-jacoby/perl/ch-1.pl
new file mode 100644
index 0000000000..0f06d19a0a
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+++ b/challenge-318/dave-jacoby/perl/ch-1.pl
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+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use experimental qw{ say state postderef signatures };
+
+my @examples = (qw{ abccccd aaabcddddeefff abcdd });
+
+for my $example (@examples) {
+    my @output = group_position($example);
+    my $output = join ', ', map { qq{"$_"} } @output;
+    say <<"END";
+    Input:  \$str = "$example"
+    Output: $output
+END
+}
+
+sub group_position ($example) {
+    return grep { length $_ > 2 } $example =~ m{
+            # (\w) matches any word character
+            # (\w)\1{2,} matches when there's one characters
+            #   that is followed by two or more identical 
+            #   characters. The form is { at least, no more than}
+            # ((\w)\1) would give problems because it's trying to
+            #   use the outer match
+            # ((\w)\2) would return first the repeated characters 
+            #   (like "aa") and then the first match itself ("a")
+            # ((\w)\2{2,}) returns the "aaaaa" and then the "a"
+            # 
+            # there is perhaps magic that allows (\w) to be used 
+            # within the regex but pass out, but I don't know it.
+            # Therefore the grep.
+            # 
+            # also //x allows you to comment your complex regular
+            # expressions.
+
+            ( (\w)\2{2,} )
+            }gmx;
+}
+
diff --git a/challenge-318/dave-jacoby/perl/ch-2.pl b/challenge-318/dave-jacoby/perl/ch-2.pl
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+++ b/challenge-318/dave-jacoby/perl/ch-2.pl
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+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use experimental qw{ say state postderef signatures };
+
+my @examples = (
+
+    [ [ 3, 2, 1, 4 ], [ 1, 2, 3, 4 ], ],
+    [
+        [ 1, 3, 4 ],
+        [ 4, 1, 3 ],
+    ],
+    [
+        [2],
+        [2],
+    ],
+
+);
+
+for my $example (@examples) {
+    my $source = join ', ', $example->[0]->@*;
+    my $target = join ', ', $example->[1]->@*;
+    my $output = reverse_equals($example);
+    say <<"END";
+        Input:  \@source = ($source)
+                \@target = ($target)
+        Output: $output
+END
+}
+
+sub reverse_equals ($obj) {
+    my @source = $obj->[0]->@*;
+    my @target = $obj->[1]->@*;
+    my $s      = join ' ', @source;
+    my $t      = join ' ', @target;
+    return 'true' if $s eq $t;
+
+    for my $i ( 0 .. $#source ) {
+        for my $j ( $i + 1 .. $#source ) {
+            my @copy = map { $_ } @source;
+            $copy[$i] = $source[$j];
+            $copy[$j] = $source[$i];
+            my $t    = join ' ', @target;
+            my $c    = join ' ', @copy;
+            return 'true' if $c eq $t;
+        }
+    }
+
+    return 'false';
+}