From 58541a2f0aa3b98156e6ca6e6d250524a7e95097 Mon Sep 17 00:00:00 2001
From: Flavio Poletti <flavio@polettix.it>
Date: Fri, 31 Mar 2023 16:16:23 +0200
Subject: Add polettix's solution to challenge-210

---
 challenge-210/polettix/blog.txt       |  1 +
 challenge-210/polettix/blog1.txt      |  1 +
 challenge-210/polettix/perl/ch-1.pl   | 30 +++++++++++++++++++++++++
 challenge-210/polettix/perl/ch-2.pl   | 42 +++++++++++++++++++++++++++++++++++
 challenge-210/polettix/raku/ch-1.raku | 29 ++++++++++++++++++++++++
 challenge-210/polettix/raku/ch-2.raku | 38 +++++++++++++++++++++++++++++++
 6 files changed, 141 insertions(+)
 create mode 100644 challenge-210/polettix/blog.txt
 create mode 100644 challenge-210/polettix/blog1.txt
 create mode 100644 challenge-210/polettix/perl/ch-1.pl
 create mode 100644 challenge-210/polettix/perl/ch-2.pl
 create mode 100644 challenge-210/polettix/raku/ch-1.raku
 create mode 100644 challenge-210/polettix/raku/ch-2.raku

diff --git a/challenge-210/polettix/blog.txt b/challenge-210/polettix/blog.txt
new file mode 100644
index 0000000000..d01e1098a2
--- /dev/null
+++ b/challenge-210/polettix/blog.txt
@@ -0,0 +1 @@
+https://etoobusy.polettix.it/2023/03/30/pwc210-kill-and-win/
diff --git a/challenge-210/polettix/blog1.txt b/challenge-210/polettix/blog1.txt
new file mode 100644
index 0000000000..d916718554
--- /dev/null
+++ b/challenge-210/polettix/blog1.txt
@@ -0,0 +1 @@
+https://etoobusy.polettix.it/2023/03/31/pwc210-number-collision/
diff --git a/challenge-210/polettix/perl/ch-1.pl b/challenge-210/polettix/perl/ch-1.pl
new file mode 100644
index 0000000000..d024720630
--- /dev/null
+++ b/challenge-210/polettix/perl/ch-1.pl
@@ -0,0 +1,30 @@
+#!/usr/bin/env perl
+use v5.24;
+use warnings;
+use experimental 'signatures';
+
+say kill_and_win(@ARGV);
+
+sub kill_and_win (@args) {
+   my $best_score = 0;
+   my $score = 0;
+   my $previous = 0;
+   my $n_streak = 0;
+   my $close_streak = sub {
+      return if $n_streak < 1;  # should not happen
+      $score = $previous if $n_streak == 1; # "singleton"
+      $best_score = $score if $score > $best_score;
+      $score = 0;
+      $n_streak = 0;
+   };
+
+   for my $item (sort { $a <=> $b } @args) {
+      $close_streak->() if $item > $previous + 1;
+      $n_streak++       if $item > $previous;
+      $score += $item;
+      $previous = $item;
+   }
+   $close_streak->();
+
+   return $best_score;
+}
diff --git a/challenge-210/polettix/perl/ch-2.pl b/challenge-210/polettix/perl/ch-2.pl
new file mode 100644
index 0000000000..475feba5a6
--- /dev/null
+++ b/challenge-210/polettix/perl/ch-2.pl
@@ -0,0 +1,42 @@
+#!/usr/bin/env perl
+use v5.24;
+use warnings;
+use experimental 'signatures';
+
+my @nc = number_collision(@ARGV);
+{ local $" = ', '; say "(@nc)" }
+
+sub number_collision (@list) {
+   my (@pre, @post); # safe items on the left and on the right
+
+   while ('necessary') {
+      push @pre,     shift @list while @list && $list[0] < 0;
+      unshift @post, pop @list   while @list && $list[-1] > 0;
+      last if scalar(@list) == 0;
+
+      my @mid;
+      INDEX:
+      for my $i (0 .. $#list) {
+         my $item = $list[$i];
+         if ($item > 0) { # try to move right
+            push @mid, $item if $item + $list[$i + 1] > 0;
+         }
+         elsif ($item < 0) { # try to move left
+            push @mid, $item if $item + $list[$i - 1] < 0;
+         }
+         else { # try to stay put
+            my $safe_left  = ($i == 0) || ($list[$i - 1] <= 0);
+            my $safe_right = ($i == $#list) || ($list[$i + 1] >= 0);
+            push @mid, 0 if $safe_left && $safe_right;
+         }
+      }
+
+      # stop simulation if nothing changed in this pass
+      last if scalar(@list) == scalar(@mid);
+
+      # go to next iteration with surviving items in the middle
+      @list = @mid;
+   }
+
+   return (@pre, @list, @post)
+}
diff --git a/challenge-210/polettix/raku/ch-1.raku b/challenge-210/polettix/raku/ch-1.raku
new file mode 100644
index 0000000000..8b8e3ad975
--- /dev/null
+++ b/challenge-210/polettix/raku/ch-1.raku
@@ -0,0 +1,29 @@
+#!/usr/bin/env raku
+use v6;
+sub MAIN (*@args) { put kill-and-win(@args) }
+
+sub kill-and-win-basic (@args) { return @args.sum }
+
+sub kill-and-win (@args) {
+   my $best-score = 0;
+   my $score = 0;
+   my $previous = 0;
+   my $n-streak = 0;
+   sub close-streak {
+      return if $n-streak < 1;
+      $score = $previous if $n-streak == 1; # "singleton"
+      $best-score = $score if $score > $best-score;
+      $score = 0;
+      $n-streak = 0;
+   }
+
+   for @args.sort({$^a <=> $^b}) -> $item {
+      close-streak() if $item > $previous + 1;
+      $n-streak++    if $item > $previous;
+      $score += $item;
+      $previous = $item;
+   }
+   close-streak();
+
+   return $best-score;
+}
diff --git a/challenge-210/polettix/raku/ch-2.raku b/challenge-210/polettix/raku/ch-2.raku
new file mode 100644
index 0000000000..7125640fda
--- /dev/null
+++ b/challenge-210/polettix/raku/ch-2.raku
@@ -0,0 +1,38 @@
+#!/usr/bin/env raku
+use v6;
+sub MAIN (*@args) { put '(', number-collision(@args).join(', '), ')' }
+
+sub number-collision (@list is copy) {
+   my (@pre, @post); # safe items on the left and on the right
+
+   loop {
+      @pre.push:     @list.shift while @list && @list[0] < 0;
+      @post.unshift: @list.pop   while @list && @list[*-1] > 0;
+      last if @list == 0;
+
+      my @mid;
+      INDEX:
+      for ^@list -> $i {
+         my $item = @list[$i];
+         if $item > 0 { # try to move right
+            @mid.push: $item if $item + @list[$i + 1] > 0;
+         }
+         elsif $item < 0 { # try to move left
+            @mid.push: $item if $item + @list[$i - 1] < 0;
+         }
+         else { # try to stay put
+            my $safe-left  = ($i == 0) || (@list[$i - 1] <= 0);
+            my $safe-right = ($i == @list.end) || (@list[$i + 1] >= 0);
+            @mid.push: 0 if $safe-left && $safe-right;
+         }
+      }
+
+      # stop simulation if nothing changed in this pass
+      last if @list.elems == @mid.elems;
+
+      # go to next iteration with surviving items in the middle
+      @list = @mid;
+   }
+
+   return (@pre, @list, @post).flat.Array;
+}
-- 
cgit