From e2e4a57c3e76e6131a7b49cd35cfb1f17b34ccbd Mon Sep 17 00:00:00 2001
From: Flavio Poletti <flavio@polettix.it>
Date: Wed, 6 Jul 2022 22:54:51 +0200
Subject: Add polettix's solution to challenge-172

---
 challenge-172/polettix/blog.txt       |  1 +
 challenge-172/polettix/blog1.txt      |  1 +
 challenge-172/polettix/perl/ch-1.pl   | 70 +++++++++++++++++++++++++++++++++++
 challenge-172/polettix/perl/ch-2.pl   | 29 +++++++++++++++
 challenge-172/polettix/raku/ch-1.raku | 12 ++++++
 challenge-172/polettix/raku/ch-2.raku | 27 ++++++++++++++
 6 files changed, 140 insertions(+)
 create mode 100644 challenge-172/polettix/blog.txt
 create mode 100644 challenge-172/polettix/blog1.txt
 create mode 100644 challenge-172/polettix/perl/ch-1.pl
 create mode 100644 challenge-172/polettix/perl/ch-2.pl
 create mode 100644 challenge-172/polettix/raku/ch-1.raku
 create mode 100644 challenge-172/polettix/raku/ch-2.raku

diff --git a/challenge-172/polettix/blog.txt b/challenge-172/polettix/blog.txt
new file mode 100644
index 0000000000..405bfff3f5
--- /dev/null
+++ b/challenge-172/polettix/blog.txt
@@ -0,0 +1 @@
+https://github.polettix.it/ETOOBUSY/2022/07/06/pwc172-prime-partition/
diff --git a/challenge-172/polettix/blog1.txt b/challenge-172/polettix/blog1.txt
new file mode 100644
index 0000000000..63451e15fb
--- /dev/null
+++ b/challenge-172/polettix/blog1.txt
@@ -0,0 +1 @@
+https://github.polettix.it/ETOOBUSY/2022/07/07/pwc172-five-number-summary/
diff --git a/challenge-172/polettix/perl/ch-1.pl b/challenge-172/polettix/perl/ch-1.pl
new file mode 100644
index 0000000000..d2cb1ad3ec
--- /dev/null
+++ b/challenge-172/polettix/perl/ch-1.pl
@@ -0,0 +1,70 @@
+#!/usr/bin/env perl
+use v5.24;
+use warnings;
+use experimental 'signatures';
+no warnings 'experimental::signatures';
+use List::Util 'sum';
+
+my $n = shift // 18;
+my $m = shift // 2;
+say simple_stringify_array(prime_partition($n, $m));
+
+sub simple_stringify_array (@a) { return '(' . join(', ', @a), ')' }
+
+sub prime_partition ($n, $m) {
+   if ($m == 1) { return is_prime($n) ? $n : () }
+   my $cit = combinations_iterator($m, primes_within(2, $n - 2));
+   while (my ($c) = $cit->()) {
+      return $c->@* if $n == sum $c->@*;
+   }
+   return;
+}
+
+sub combinations_iterator ($k, @items) {
+   my @indexes = (0 .. ($k - 1));
+   my $n = @items;
+   return sub {
+      return unless @indexes;
+      my (@combination, @remaining);
+      my $j = 0;
+      for my $i (0 .. ($n - 1)) {
+         if ($j < $k && $i == $indexes[$j]) {
+            push @combination, $items[$i];
+            ++$j;
+         }
+         else {
+            push @remaining, $items[$i];
+         }
+      }
+      for my $incc (reverse(-1, 0 .. ($k - 1))) {
+         if ($incc < 0) {
+            @indexes = (); # finished!
+         }
+         elsif ((my $v = $indexes[$incc]) < $incc - $k + $n) {
+            $indexes[$_] = ++$v for $incc .. ($k - 1);
+            last;
+         }
+      }
+      return (\@combination, \@remaining);
+   }
+}
+
+sub primes_within ($min, $max) {
+   my @retval = $min < 3 ? 2 : ();
+   $min++ unless $min % 2;
+   while ($min <= $max) {
+      push @retval, $min if is_prime($min);
+      $min += 2;
+   }
+   return @retval;
+}
+
+sub is_prime { # https://en.wikipedia.org/wiki/Primality_test
+   return if $_[0] < 2;
+   return 1 if $_[0] <= 3;
+   return unless ($_[0] % 2) && ($_[0] % 3);
+   for (my $i = 6 - 1; $i * $i <= $_[0]; $i += 6) {
+      return unless ($_[0] % $i) && ($_[0] % ($i + 2));
+   }
+   return 1;
+}
diff --git a/challenge-172/polettix/perl/ch-2.pl b/challenge-172/polettix/perl/ch-2.pl
new file mode 100644
index 0000000000..62785c29b1
--- /dev/null
+++ b/challenge-172/polettix/perl/ch-2.pl
@@ -0,0 +1,29 @@
+#!/usr/bin/env perl
+use v5.24;
+use warnings;
+use experimental 'signatures';
+no warnings 'experimental::signatures';
+
+my @values = (0, 0, 1, 2, 63, 61, 27, 13);
+my @fives = five_number_summary(@values);
+say "(@fives)";
+
+sub five_number_summary (@input) {
+   state $emedian = sub ($aref, $from, $to) {
+      my $twom = $from + $to;
+      my $rem  = $twom % 2;
+      my $lo = ($twom - $rem) / 2;
+      my $hi = $lo + 1;
+      my $medn = $rem ? ($aref->[$lo] + $aref->[$hi]) / 2 : $aref->[$lo];
+
+      # https://en.wikipedia.org/wiki/Quartile - Tukey's hinges
+      return ($medn, $rem ? ($lo, $hi) : ($lo, $lo));
+   };
+   @input = sort { $a <=> $b } @input;
+
+   my ($median, $lo, $hi) = $emedian->(\@input, 0, $#input);
+   my ($lop) = $emedian->(\@input, 0, $lo);
+   my ($hip) = $emedian->(\@input, $hi, $#input);
+
+   return ($input[0], $lop, $median, $hip, $input[-1]);
+}
diff --git a/challenge-172/polettix/raku/ch-1.raku b/challenge-172/polettix/raku/ch-1.raku
new file mode 100644
index 0000000000..7bf4b0cef6
--- /dev/null
+++ b/challenge-172/polettix/raku/ch-1.raku
@@ -0,0 +1,12 @@
+#!/usr/bin/env raku
+use v6;
+sub MAIN ($n = 18, $m = 2) { say prime-partition($n, $m) }
+
+multi sub prime-partition ($n where *.is-prime, 1) { [ $n ] }
+multi sub prime-partition ($n, 1) { [] }
+multi sub prime-partition ($n, $m) {
+   for (2 .. $n - 2).grep({.is-prime}).combinations($m) -> $c {
+      return $c.Array if $c.sum == $n;
+   }
+   return [];
+}
diff --git a/challenge-172/polettix/raku/ch-2.raku b/challenge-172/polettix/raku/ch-2.raku
new file mode 100644
index 0000000000..8249be70a4
--- /dev/null
+++ b/challenge-172/polettix/raku/ch-2.raku
@@ -0,0 +1,27 @@
+#!/usr/bin/env raku
+use v6;
+sub MAIN {
+   my @values = (0, 0, 1, 2, 63, 61, 27, 13);
+   my @fives = five-number-summary(@values);
+   say @fives;
+}
+
+sub five-number-summary (*@input) {
+   sub emedian ($from, $to) {
+      my $twom = $from + $to;
+      my $rem  = $twom % 2;
+      my $lo = ($twom - $rem) / 2;
+      my $hi = $lo + 1;
+      my $medn = $rem ?? (@input[$lo] + @input[$hi]) / 2 !! @input[$lo];
+
+      # https://en.wikipedia.org/wiki/Quartile - Tukey's hinges
+      return [$medn, $rem ?? |($lo, $hi) !! |($lo, $lo)];
+   }
+   @input = @input.sort: { $^a <=> $^b };
+
+   my ($median, $lo, $hi) = emedian(0, @input.end);
+   my ($lop) = emedian(0, $lo);
+   my ($hip) = emedian($hi, @input.end);
+
+   return [@input[0], $lop, $median, $hip, @input[*-1]];
+}
-- 
cgit