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#include <array>
#include <fstream>
#include <iostream>
#include <sstream>
using namespace std;
struct Item {
Item(string_view name, int cost, int damage, int armor)
: name_(name)
, cost_(cost)
, damage_(damage)
, armor_(armor)
{
}
const string name_;
const int cost_;
const int damage_;
const int armor_;
};
struct Boss {
int hit_points_;
int damage_;
int armor_;
};
struct Player {
Player(const Item& weapon, const Item& armor, const tuple<Item, Item>& rings)
: damage_(weapon.damage_ + armor.damage_ + get<0>(rings).damage_ + get<1>(rings).damage_)
, armor_(weapon.armor_ + armor.armor_ + get<0>(rings).armor_ + get<1>(rings).armor_)
{
}
int hit_points_{ 100 };
int damage_;
int armor_;
bool would_win_against(Boss boss)
{
while ( true ) {
auto player_damage = max(1, damage_ - boss.armor_);
boss.hit_points_ -= player_damage;
if ( boss.hit_points_ <= 0 ) {
return true;
}
auto boss_damage = max(1, boss.damage_ - armor_);
hit_points_ -= boss_damage;
if ( hit_points_ <= 0 ) {
return false;
}
}
}
};
const array<Item, 5> weapons = {
Item("Dagger", 8, 4, 0),
Item("Shortsword", 10, 5, 0),
Item("Warhammer", 25, 6, 0),
Item("Longsword", 40, 7, 0),
Item("Greataxe", 74, 8, 0)
};
const array<Item, 6> armors = {
Item("Leather", 13, 0, 1),
Item("Chainmail", 31, 0, 2),
Item("Splintmail", 53, 0, 3),
Item("Bandedmail", 75, 0, 4),
Item("Platemail", 102, 0, 5),
Item("Noting", 0, 0, 0)
};
vector<tuple<Item, Item>>
generate_ring_pairs()
{
const array<Item, 7> rings = {
Item("Damage +1", 25, 1, 0),
Item("Damage +2", 50, 2, 0),
Item("Damage +3", 100, 3, 0),
Item("Defense +1", 20, 0, 1),
Item("Defense +2", 40, 0, 2),
Item("Defense +3", 80, 0, 3),
Item("Nothing 0", 0, 0, 0)
};
vector<tuple<Item, Item>> pairs;
for ( size_t i = 0; i < rings.size(); ++i ) {
for ( size_t j = i + 1; j < rings.size(); ++j ) {
pairs.emplace_back(rings.at(i), rings.at(j));
}
}
pairs.emplace_back(rings.back(), rings.back());
return pairs;
}
auto
split(const string& line, char sep = ' ')
{
vector<string> parts;
stringstream input{ line };
for ( string part; getline(input, part, sep); ) {
parts.emplace_back(part);
}
return parts;
}
Boss
read_file(string_view filename)
{
fstream input{ filename };
Boss boss{};
for ( string line; getline(input, line); ) {
auto parts = split(line);
if ( parts[0] == "Hit" ) {
boss.hit_points_ = stoi(parts[2]);
}
else if ( parts[0] == "Damage:" ) {
boss.damage_ = stoi(parts[1]);
}
else if ( parts[0] == "Armor:" ) {
boss.armor_ = stoi(parts[1]);
}
}
return boss;
}
void
part1(const Boss& boss)
{
auto rings = generate_ring_pairs();
auto min_cost = numeric_limits<int>::max();
for ( const auto& weapon: weapons ) {
for ( const auto& armor: armors ) {
for ( const auto& ring_pair: rings ) {
Player player(weapon, armor, ring_pair);
if (player.would_win_against(boss)) {
min_cost = min(min_cost, weapon.cost_ + armor.cost_ + get<0>(ring_pair).cost_ + get<1>(ring_pair).cost_);
}
}
}
}
cout << min_cost << endl;
}
void
part2(const Boss& boss)
{
auto rings = generate_ring_pairs();
auto max_cost = numeric_limits<int>::min();
for ( const auto& weapon: weapons ) {
for ( const auto& armor: armors ) {
for ( const auto& ring_pair: rings ) {
Player player(weapon, armor, ring_pair);
if (!player.would_win_against(boss)) {
max_cost = max(max_cost, weapon.cost_ + armor.cost_ + get<0>(ring_pair).cost_ + get<1>(ring_pair).cost_);
}
}
}
}
cout << max_cost << endl;
}
int
main()
{
auto boss = read_file("data/day21.txt");
part1(boss);
part2(boss);
}
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