rjt's week 77 Perl solutions (v. belated)

3 files changed, 71 insertions, 8 deletions

diff --git a/challenge-077/ryan-thompson/README.md b/challenge-077/ryan-thompson/README.md
index 698e3ee64f..92d6fbb5b7 100644
--- a/challenge-077/ryan-thompson/README.md
+++ b/challenge-077/ryan-thompson/README.md
@@ -1,19 +1,15 @@
 # Ryan Thompson
 
-## Week 056 Solutions
+## Week 077 Solutions
 
-### Task 1 › Diff-K
+### Task 1 › Fibonacci Sum
 
  * [Perl](perl/ch-1.pl)
- * [Raku](raku/ch-1.p6)
 
-### Task 2 › Path Sum
+### Task 2 › Lonely X
 
  * [Perl](perl/ch-2.pl)
- * [Raku](raku/ch-2.p6)
 
 ## Blogs
 
- * [Diff-K](https://ry.ca/2020/04/diff-k/)
- * [Path Sum](https://ry.ca/2020/04/path-sum/)
-
+ * None this week.
diff --git a/challenge-077/ryan-thompson/perl/ch-1.pl b/challenge-077/ryan-thompson/perl/ch-1.pl
new file mode 100755
index 0000000000..a1b3dd7c29
--- /dev/null
+++ b/challenge-077/ryan-thompson/perl/ch-1.pl
@@ -0,0 +1,25 @@
+#!/usr/bin/env perl
+#
+# ch-1.pl - Fibonacci Sum
+#
+# 2022 Ryan Thompson <rjt@cpan.org>
+
+use 5.016;
+use warnings;
+use strict;
+no warnings 'uninitialized';
+
+my $N = shift // die "Usage: $0 <integer>\n";
+
+my @fib = (1,2);
+push @fib, $fib[-1] + $fib[-2] while $fib[-1] < $N;
+pop @fib if $fib[-1] > $N;
+
+sub {
+    my $n = shift;
+
+    return say join(" + ", @_) . " == $N" if $n == 0;
+
+    __SUB__->($n-$_, @_, $_) for grep { $_ <= $n and $_ > $_[-1] } @fib;
+
+}->($N);
diff --git a/challenge-077/ryan-thompson/perl/ch-2.pl b/challenge-077/ryan-thompson/perl/ch-2.pl
new file mode 100755
index 0000000000..170a3977dd
--- /dev/null
+++ b/challenge-077/ryan-thompson/perl/ch-2.pl
@@ -0,0 +1,42 @@
+#!/usr/bin/env perl
+#
+# ch-2.pl - Lonely X
+#
+# 2022 Ryan Thompson <rjt@cpan.org>
+
+use 5.010;
+use warnings;
+use strict;
+use List::Util qw< any all >;
+
+sub X() { $_->[1] }  # Convenient aliases
+sub Y() { $_->[0] }  # (syntactic sugar!)
+
+my @ex2 = ([ qw< o o x o > ],
+           [ qw< x o o o > ],
+           [ qw< x o o x > ],
+           [ qw< o x o o > ]);
+
+say "There are " . lonely_x(@ex2) . " lonely 'x's";
+
+sub lonely_x {
+    my $xmax = $#{$_[0]};
+    my $count = 0;
+
+    for my $y (0..$#_) {
+        for my $x (0..$xmax) {
+            next if $_[$y][$x] ne 'x';
+
+            next if any {     $_[Y][X] eq 'x'    }
+                   grep {  Y >= 0 && Y <= $#_
+                    and    X >= 0 && X <= $xmax  }
+                    map {     [ $y+Y, $x+X ]     }
+                   grep { not (X == 0 && Y == 0) }
+                    map { my $yp = $_; map { [$yp,$_] } -1..1 } -1..1;
+
+            say "x at row $y, col $x is lonely";
+            $count++;
+        }
+    }
+    $count;
+}