Day 13

d13/main.cxx

@@ -1,15 +1,158 @@
+#include <string>
+#include <sstream>
+#include <chrono>
 #include <iostream>
-#include <fstream>
+#include <vector>
+#include <ranges>
 
 using std::cout, std::endl;
 
-int main() {
-    std::ifstream file{"../d13/input.txt"};
-    std::string line;
+namespace views = std::ranges::views;
 
-    while (std::getline(file, line)) {
+constexpr const char content[] = {
+    #embed "input.txt"
+};
+
+struct Config {
+    std::pair<uint64_t, uint64_t> a_button;
+    std::pair<uint64_t, uint64_t> b_button;
+    std::pair<uint64_t, uint64_t> prize;
+};
+
+uint64_t part_1() {
+    std::istringstream input_stream(content);
+    std::string line, ignore, val_str;
+    std::vector<Config> configs = {};
+    while(getline(input_stream, line)) {
+        if(line.empty()) {
+            continue;
+        }
+
+        std::istringstream line_stream(line);
+        Config config = {};
+
+        line_stream >> ignore >> ignore >> val_str;
+        config.a_button.first = std::stoll(val_str.substr(val_str.find('+')+1, val_str.size()-3));
+        line_stream >> val_str;
+        config.a_button.second = std::stoll(val_str.substr(val_str.find('+')+1, val_str.size()-2));
+
+        getline(input_stream, line);
+        line_stream = std::istringstream(line);
+        line_stream >> ignore >> ignore >> val_str;
+        config.b_button.first = std::stoll(val_str.substr(val_str.find('+')+1, val_str.size()-3));
+        line_stream >> val_str;
+        config.b_button.second = std::stoll(val_str.substr(val_str.find('+')+1, val_str.size()-2));
+
+        getline(input_stream, line);
+        line_stream = std::istringstream(line);
+
+        line_stream >> ignore >> val_str;
+        config.prize.first = std::stoll(val_str.substr(val_str.find('=')+1, val_str.size()-3)); 
+        line_stream >> val_str;
+        config.prize.second = std::stoll(val_str.substr(val_str.find('=')+1, val_str.size()-2));
+
+        configs.push_back(config);
+    }
+
+    constexpr auto a_press_cost = 3;
+    constexpr auto b_press_cost = 1;
+    uint64_t acc{0};
+    
+    for(auto& config : configs) {
+        int64_t det = config.a_button.first * config.b_button.second - config.a_button.second * config.b_button.first;
+        int64_t det_x = config.prize.first * config.b_button.second - config.prize.second * config.b_button.first;
+        int64_t det_y = config.a_button.first * config.prize.second - config.prize.first * config.a_button.second;
+
+        if(det == 0) {
+            continue;
+        } 
+
+        int64_t a_presses = det_x / det;
+        int64_t b_presses = det_y / det;
+
+        if(a_presses * config.a_button.first + b_presses * config.b_button.first == config.prize.first 
+        && a_presses * config.a_button.second + b_presses * config.b_button.second == config.prize.second) {
+            acc += a_presses * a_press_cost + b_presses * b_press_cost;
+        }
 
     } 
 
+    return acc;
+}
+    
+
+uint64_t part_2() {
+    std::istringstream input_stream(content);
+    std::string line, ignore, val_str;
+    std::vector<Config> configs = {};
+    while(getline(input_stream, line)) {
+        if(line.empty()) {
+            continue;
+        }
+
+        std::istringstream line_stream(line);
+        Config config = {};
+
+        line_stream >> ignore >> ignore >> val_str;
+        config.a_button.first = std::stoll(val_str.substr(val_str.find('+')+1, val_str.size()-3));
+        line_stream >> val_str;
+        config.a_button.second = std::stoll(val_str.substr(val_str.find('+')+1, val_str.size()-2));
+
+        getline(input_stream, line);
+        line_stream = std::istringstream(line);
+        line_stream >> ignore >> ignore >> val_str;
+        config.b_button.first = std::stoll(val_str.substr(val_str.find('+')+1, val_str.size()-3));
+        line_stream >> val_str;
+        config.b_button.second = std::stoll(val_str.substr(val_str.find('+')+1, val_str.size()-2));
+
+        getline(input_stream, line);
+        line_stream = std::istringstream(line);
+
+        line_stream >> ignore >> val_str;
+        config.prize.first = std::stoll(val_str.substr(val_str.find('=')+1, val_str.size()-3)); 
+        line_stream >> val_str;
+        config.prize.second = std::stoll(val_str.substr(val_str.find('=')+1, val_str.size()-2));
+
+        config.prize.first += 10000000000000;
+        config.prize.second += 10000000000000;
+
+        configs.push_back(config);
+    }
+
+    constexpr auto a_press_cost = 3;
+    constexpr auto b_press_cost = 1;
+    uint64_t acc{0};
+    
+    for(auto& config : configs) {
+        int64_t det = config.a_button.first * config.b_button.second - config.a_button.second * config.b_button.first;
+        int64_t det_x = config.prize.first * config.b_button.second - config.prize.second * config.b_button.first;
+        int64_t det_y = config.a_button.first * config.prize.second - config.prize.first * config.a_button.second;
+
+        if(det == 0) {
+            continue;
+        } 
+
+        int64_t a_presses = det_x / det;
+        int64_t b_presses = det_y / det;
+
+        if(a_presses * config.a_button.first + b_presses * config.b_button.first == config.prize.first 
+        && a_presses * config.a_button.second + b_presses * config.b_button.second == config.prize.second) {
+            acc += a_presses * a_press_cost + b_presses * b_press_cost;
+        }
+
+    }
+    
+
+    return acc;
+}
+
+int main() {
+    std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
+    auto p1_val = part_1();
+    std::chrono::steady_clock::time_point middle = std::chrono::steady_clock::now();
+    auto p2_val = part_2();
+    std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
+    cout << "Part 1: " << p1_val << " (" << std::chrono::duration_cast<std::chrono::microseconds>(middle - begin).count() << "µs)" << endl;  
+    cout << "Part 2: " << p2_val << " (" << std::chrono::duration_cast<std::chrono::microseconds>(end - middle).count() << "µs)" << endl;
     return 0;
 }