Solution to task 2

1 files changed, 88 insertions, 0 deletions

diff --git a/challenge-266/jo-37/perl/ch-2.pl b/challenge-266/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..9e6de958e0
--- /dev/null
+++ b/challenge-266/jo-37/perl/ch-2.pl
@@ -0,0 +1,88 @@
+#!/usr/bin/perl -s
+
+use v5.24;
+use Test2::V0 '!float';
+use PDL;
+use PDL::NiceSlice;
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [MATRIX]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+MATRIX
+    a square matrix in any form accepted by the PDL string constructor,
+    e.g. '[ [1, 0, 0, 2], [0, 3, 4, 0], [0, 5, 6, 0], [7, 0, 0, 1] ]'
+
+EOS
+
+
+### Input and Output
+
+say +(qw(false true))[is_x("@ARGV")];
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2024/04/26/ch-266.html#task-2
+
+
+sub is_x {
+	my $m = pdl @_;
+    my ($on_x, $off_x) = $m->where_both(identity($m) | identity($m)->(-1:0));
+
+    all($on_x) && !any($off_x);
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is is_x([ [1, 0, 0, 2],
+                  [0, 3, 4, 0],
+                  [0, 5, 6, 0],
+                  [7, 0, 0, 1],
+                ]), T(), 'example 1';
+
+        is is_x([ [1, 2, 3],
+                  [4, 5, 6],
+                  [7, 8, 9],
+                ]), F(), 'example 2';
+
+        is is_x([ [1, 0, 2],
+                  [0, 3, 0],
+                  [4, 0, 5],
+                ]), T(), 'example 3';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        is is_x([ [1, 0, 0, 2],
+                  [0, 3, 4, 0],
+                  [0, 5, 6, 0],
+                  [7, 0, 0, 0],
+                ]), F(), 'zero on X';
+
+        is is_x([ [1, 0, 0, 2],
+                  [0, 3, 4, 0],
+                  [0, 5, 6, 1],
+                  [7, 0, 0, 1],
+                ]), F(), 'nonzero off X';
+	}
+
+    done_testing;
+    exit;
+}