AoC 23

day23.pl

#!/usr/bin/env perl

use strict;
use warnings;
use v5.20;

use List::Util qw/ min max /;
use Data::Dumper;

$Data::Dumper::Indent = 0;
$Data::Dumper::Terse = 1;

my $hard_mode = 1;

my @spells = (
    # name      , cost, timer, dmg, heal, armor, mana recharge
    [ 'missile' ,   53,     1,   4,    0,     0,             0 ],
    [ 'drain'   ,   73,     1,   2,    2,     0,             0 ],
    [ 'shield'  ,  113,     6,   0,    0,     7,             0 ],
    [ 'poison'  ,  173,     6,   3,    0,     0,             0 ],
    [ 'recharge',  229,     5,   0,    0,     0,           101 ]
);

my ($monster_hp, $monster_dmg) = (51, 9);
my ($hp, $mana) = (50, 500);

# my ($monster_hp, $monster_dmg) = (13, 8);
# my ($hp, $mana) = (10, 250);

# name -> spell
my %current_spells = ();

say recurse([ $hp, $mana ], [ $monster_hp, $monster_dmg ], \%current_spells, 0, 0);

sub recurse {
    my ($me, $monster, $current_spells, $mana_spent, $depth) = @_;
    
    my @manas_spent = ();
    for my $spell (@spells) {
        # copies for the recursion
        my $new_me = [ @$me ];
        my $new_monster = [ @$monster ];
        my $new_current_spells = { map
                { $_ => [ @{$current_spells->{$_}} ] }
                keys %$current_spells };
        my $new_mana_spent = $mana_spent + $spell->[1];
        
        # player turn
        if ($hard_mode) {
            $new_me->[0]--;
            if ($new_me->[0] <= 0) {
                next;
            }
        }
        apply_spells($new_me, $new_monster, $new_current_spells, $depth);
        
        next if exists $new_current_spells->{$spell->[0]};
        next if $spell->[1] > $me->[1];
        
#         msay($depth, Dumper($me) . ' v ' . $monster->[0] . ' active spells ' . join ', ', sort keys %$current_spells);
        
        
        
#         msay($depth, 'player casts ' . $spell->[0]);
        $new_me->[1] -= $spell->[1];
        if ($spell->[0] eq 'missile' || $spell->[0] eq 'drain') {
            $new_monster->[0] -= $spell->[3];
            $new_me->[0] += $spell->[4];
        } else {
            $new_current_spells->{$spell->[0]} = [ @$spell ];
        }
#         msay($depth, 'current spells now ' . join ', ', sort keys %$new_current_spells);
        
        if ($new_monster->[0] <= 0) {
#             msay($depth, "win with mana spent $new_mana_spent");
            push @manas_spent, $new_mana_spent;
            next;
        }
        
        # monster turn
        apply_spells($new_me, $new_monster, $new_current_spells, $depth);
        if ($new_monster->[0] <= 0) {
#             msay($depth, "win with mana spent $new_mana_spent");
            push @manas_spent, $new_mana_spent;
            next;
        }
        
        my $my_armor = exists $current_spells->{'shield'} ? 7 : 0;
        my $monster_dmg = max(1, $new_monster->[1] - $my_armor);
        $new_me->[0] -= $monster_dmg;
#         msay($depth, "monster attacks for $monster_dmg (armor $my_armor, @{[$new_me->[0]]} remaining)");
        if ($new_me->[0] <= 0) {
#             msay($depth, "lost!");
            next;
        }
        
        push @manas_spent, recurse($new_me, $new_monster, $new_current_spells, $new_mana_spent, $depth + 1);
    }
    
    return 100000 if 0 == scalar(@manas_spent);
    return min(@manas_spent);
}

sub apply_spells {
    my ($me, $monster, $current_spells, $depth) = @_;
    
    for my $spell_name (keys %$current_spells) {
        my $spell = $current_spells->{$spell_name};
#         msay($depth, "using $spell_name dealing @{[$spell->[3]]} damage");
        
        $monster->[0] -= $spell->[3];
        $me->[1] += $spell->[6];
        
        $spell->[2]--;
        
#         my $description = 'MISSING DESCRIPTION';
#         if ($spell_name eq 'missile') {
#             $description = "Player casts magic missile, dealing @[{$spell->[3] damage";
#         } elsif ($spell_name eq 'drain') {
#             $description = "Player casts drain, dealing @[{$spell->[3]]} damage and healing @{[$spell->[4]]} hit points";
#         } else {
#             if ($spell_name eq 'shield') {
#                 $description = 'shield';
#             } elsif ($spell_name eq 'poison') {
#                 $description = "poison deals @{[$spell->[3]]} damage";
#             } elsif ($spell_name eq 'recharge') {
#                 $description = "recharge provides @{[$spell->[6]]} mana";
#             }
#             $description .= "; it's timer is now @{[$spell->[2]]}";
#         }
#          msay($depth, $description);
#          msay($depth, $spell_name . ' wears off') if $spell->[2] <= 0;
        delete $current_spells->{$spell_name} if $spell->[2] <= 0;
    }
}

sub msay {
    my ($depth, @list) = @_;
    say '|   'x$depth, @list;
}