Solution to task 1

1 files changed, 68 insertions, 0 deletions

diff --git a/challenge-283/jo-37/perl/ch-1.pl b/challenge-283/jo-37/perl/ch-1.pl
new file mode 100755
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+++ b/challenge-283/jo-37/perl/ch-1.pl
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+#!/usr/bin/perl -s
+
+use v5.24;
+use Test2::V0;
+
+our ($tests, $examples);
+
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [N...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+N...
+    list of integers
+
+EOS
+
+
+### Input and Output
+
+say unique_number(@ARGV) // 'no single unique number';
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2024/08/23/ch-283.html#task-1
+
+sub unique_number {
+    my ($sum, $cnt, %seen) = (0, 0);
+    ($seen{$_}, $sum, $cnt) = exists $seen{$_} ?
+        (0, $sum - $seen{$_} * $_, $cnt - $seen{$_}) :
+        (1, $sum + $_, $cnt + 1) for @_;
+
+    $cnt == 1 ? $sum : undef;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+        is unique_number(3, 3, 1), 1, 'example 1';
+        is unique_number(3, 2, 4, 2, 4), 3, 'example 2';
+        is unique_number(1), 1, 'example 3';
+        is unique_number(4, 3, 1, 1, 1, 4), 3, 'example 4';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        is unique_number(1, 2, 3, 3), U(),
+            'multiple unique values';
+        is unique_number(1, 2, 3, 3, 2, 1), U(), 'no unique value';
+        is unique_number(-2, -1, 0, -2 , 0), -1, 'negative';
+	}
+
+    done_testing;
+    exit;
+}