day22-1.pl6

use v6;

my %stats =
  :boss-hp(51),
  :player-hp(50),
  :player-mana(500),
  :shield(0),
  :poison(0),
  :recharge(0),
  :elapsed(0);

my $recharge-max-mana = 229 + 53;
my $recharge-min-mana = 229;
my $boss-dmg = 9;

sub evolve(%stats is copy, $move) {
  if %stats<poison> {
    %stats<boss-hp> -= 3;
    --%stats<poison>;
  }
  if %stats<recharge> {
    %stats<player-mana> += 101;
    --%stats<recharge>;
  }
  if %stats<shield> {
    --%stats<shield>;
  }
  my $om = %stats<player-mana>;
  given $move {
    when "MagicMissile" {
      %stats<player-mana> -= 53;
      %stats<boss-hp> -= 4;
    }
    when "Drain" {
      %stats<player-mana> -= 73;
      %stats<boss-hp> -= 2;
      %stats<player-hp> += 2;
    }
    when "Shield" {
      return Nil if %stats<shield>;
      %stats<player-mana> -= 113;
      %stats<shield> = 6;
    }
    when "Poison" {
      return Nil if %stats<poison>;
      %stats<player-mana> -= 173;
      %stats<poison> = 6;
    }
    when "Recharge" {
      return Nil if %stats<recharge>;
      %stats<player-mana> -= 229;
      %stats<recharge> = 5;
    }
  }
  %stats<elapsed> += $om - %stats<player-mana>;
  return Nil if %stats<player-mana> < 0;
  if %stats<poison> {
    %stats<boss-hp> -= 3;
    --%stats<poison>;
  }
  if %stats<recharge> {
    %stats<player-mana> += 101;
    --%stats<recharge>;
  }
  if %stats<shield> {
    %stats<player-hp> += 7;
    --%stats<shield>;
  }
  %stats<player-hp> -= $boss-dmg;
  return Nil if %stats<player-hp> <= 0 && %stats<boss-hp> > 0;
  return Nil if %stats<player-mana> < 53 && %stats<boss-hp> > 0;
  return %stats;
}

sub min-turns(%stats, $elapsed) {
  state $min = Inf;
  return Inf if %stats<elapsed> >= $min;
  if %stats<boss-hp> <= 0 && %stats<elapsed> < $min {
    $min = %stats<elapsed>;
    say "New record $min at $elapsed";
    return $min;
  }
  my @res = <MagicMissile Drain Shield Poison Recharge>.map({evolve(%stats, $_)}).grep(Associative);
  if my @winners = @res.grep({$_<boss-hp> <= 0 && $_<elapsed> < $min}) {
    $min = min @winners.map(*<elapsed>);
    say "New record $min at $elapsed";
    return $min;
  }
  return min @res.map({min-turns($_, $elapsed + 1)});
}

say min-turns(%stats, 0);

day22-2.pl6

use v6;

my %stats =
  :boss-hp(51),
  :player-hp(50),
  :player-mana(500),
  :shield(0),
  :poison(0),
  :recharge(0),
  :elapsed(0);

my $recharge-max-mana = 229 + 53;
my $recharge-min-mana = 229;
my $boss-dmg = 9;

sub evolve(%stats is copy, $move) {
  if %stats<poison> {
    %stats<boss-hp> -= 3;
    --%stats<poison>;
  }
  if %stats<recharge> {
    %stats<player-mana> += 101;
    --%stats<recharge>;
  }
  if %stats<shield> {
    --%stats<shield>;
  }
  return Nil if --%stats<player-hp> <= 0;
  my $om = %stats<player-mana>;
  given $move {
    when "MagicMissile" {
      %stats<player-mana> -= 53;
      %stats<boss-hp> -= 4;
    }
    when "Drain" {
      %stats<player-mana> -= 73;
      %stats<boss-hp> -= 2;
      %stats<player-hp> += 2;
    }
    when "Shield" {
      return Nil if %stats<shield>;
      %stats<player-mana> -= 113;
      %stats<shield> = 6;
    }
    when "Poison" {
      return Nil if %stats<poison>;
      %stats<player-mana> -= 173;
      %stats<poison> = 6;
    }
    when "Recharge" {
      return Nil if %stats<recharge>;
      %stats<player-mana> -= 229;
      %stats<recharge> = 5;
    }
  }
  %stats<elapsed> += $om - %stats<player-mana>;
  return Nil if %stats<player-mana> < 0;
  if %stats<poison> {
    %stats<boss-hp> -= 3;
    --%stats<poison>;
  }
  if %stats<recharge> {
    %stats<player-mana> += 101;
    --%stats<recharge>;
  }
  if %stats<shield> {
    %stats<player-hp> += 7;
    --%stats<shield>;
  }
  %stats<player-hp> -= $boss-dmg;
  return Nil if %stats<player-hp> <= 0 && %stats<boss-hp> > 0;
  return Nil if %stats<player-mana> < 53 && %stats<boss-hp> > 0;
  return %stats;
}

sub min-turns(%stats, $elapsed) {
  state $min = Inf;
  return Inf if %stats<elapsed> >= $min;
  if %stats<boss-hp> <= 0 && %stats<elapsed> < $min {
    $min = %stats<elapsed>;
    say "New record $min at $elapsed";
    return $min;
  }
  my @res = <MagicMissile Drain Shield Poison Recharge>.map({evolve(%stats, $_)}).grep(Associative);
  if my @winners = @res.grep({$_<boss-hp> <= 0 && $_<elapsed> < $min}) {
    $min = min @winners.map(*<elapsed>);
    say "New record $min at $elapsed";
    return $min;
  }
  return min @res.map({min-turns($_, $elapsed + 1)});
}

say min-turns(%stats, 0);