2 files changed, 100 insertions, 0 deletions
diff --git a/challenge-201/jo-37/perl/ch-1.pl b/challenge-201/jo-37/perl/ch-1.pl
new file mode 100755
index 0000000000..6ef767bbc8
--- /dev/null
+++ b/challenge-201/jo-37/perl/ch-1.pl
@@ -0,0 +1,96 @@
+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use List::Util 'sum';
+use experimental 'postderef';
+use Benchmark 'cmpthese';
+
+our ($tests, $examples, $benchmark, $single);
+
+run_tests() if $tests || $examples || $benchmark;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [-benchmark] [-single] [--] [N...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+-benchmark
+    benchmark different branches
+
+-single
+    assume one single missing value as suggested by the examples
+
+N...
+    list of unique numbers
+
+EOS
+
+
+### Input and Output
+
+say for find_missing($single, @ARGV);
+
+
+### Implementation
+
+# If the given unique numbers were in the range 0 .. N, then exactly one
+# number would be missing and this could easily be found as the
+# difference between the sum over all numbers up to N and the sum over
+# the given numbers.  The examples conform to this pattern but it is not
+# stated explicitly. Therefore the more efficient implementation must be
+# chosen with a 'true' first argument.
+
+sub find_missing {
+    # The easy way:
+    return @_ * (@_ + 1) / 2 - sum @_ if shift;
+
+    # The hard way:
+    (\my %num)->@{0 .. @_} = ();
+    delete @num{@_};
+    sort {$a <=> $b} keys %num;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is [find_missing(-single, 0, 1, 3)], [2], 'example 1, single';
+        is [find_missing(undef,   0, 1, 3)], [2], 'example 1, multi';
+        is [find_missing(-single, 0, 1)],    [2], 'example 2, single';
+        is [find_missing(undef,   0, 1)],    [2], 'example 2, multi';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        is [find_missing(undef, 4, 7, -1)], [0 .. 3], 'nothing in list';
+	}
+
+    SKIP: {
+        skip "benchmark" unless $benchmark;
+
+        is [find_missing(-single, 1 .. 1000000)], [0], 'sum';
+        is [find_missing(undef,   1 .. 1000000)], [0], 'hash';
+
+        cmpthese(0, {
+                sum  => sub {find_missing(-single, 1 .. 1000000)},
+                hash => sub {find_missing(undef,   1 .. 1000000)},
+            });
+    }
+
+    done_testing;
+    exit;
+}
+
+__DATA__
+       Rate  hash   sum
+hash 1.47/s    --  -97%
+sum  48.2/s 3187%    --
diff --git a/challenge-201/jo-37/perl/ch-2.sh b/challenge-201/jo-37/perl/ch-2.sh
new file mode 100755
index 0000000000..ba66afd8c3
--- /dev/null
+++ b/challenge-201/jo-37/perl/ch-2.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+# Find the number of partitions
+perl -MMath::Prime::Util=:all -E 'say partitions shift' $1