Solution to task 2

1 files changed, 68 insertions, 0 deletions

diff --git a/challenge-196/jo-37/perl/ch-2.pl b/challenge-196/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..6019c07fac
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+++ b/challenge-196/jo-37/perl/ch-2.pl
@@ -0,0 +1,68 @@
+#!/usr/bin/perl -s
+
+use v5.16;
+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 number to be searched for contiguous intervals.
+
+EOS
+
+
+### Input and Output
+
+main: {
+    local $, = ', ';
+    local $" = ', ';
+    say map "[@$_]", range_list(@ARGV);
+}
+
+### Implementation
+
+sub range_list {
+    # Collect contiguous intervals:
+    my @int = (['-inf']);
+
+    # If the current number is the successor of the current interval's
+    # last seen element, take it as the new interval endpoint.  Start a
+    # new interval otherwise.
+    $_ == $int[-1][-1] + 1 ? $int[-1][1] = $_ : push @int, [$_] for @_;
+
+    # Discard point-only intervals.
+    grep @$_ > 1, @int;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is [range_list(1, 3, 4, 5, 7)], [[3, 5]], 'example 1';
+        is [range_list(1, 2, 3, 6, 7, 9)], [[1, 3], [6, 7]], 'example 2';
+        is [range_list(0, 1, 2, 4, 5, 6, 8, 9)], [[0, 2], [4, 6], [8, 9]],
+            'example 3';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+        is [range_list(0, 2, 4, 6, 8)], [], 'none';
+	}
+
+    done_testing;
+    exit;
+}