Day 11

d11/main.cxx

@@ -1,15 +1,82 @@
+#include <string>
+#include <sstream>
+#include <chrono>
 #include <iostream>
-#include <fstream>
+#include <vector>
+#include <unordered_map>
 
 using std::cout, std::endl;
 
-int main() {
+constexpr const char content[] = {
-    std::ifstream file{"../d11/input.txt"};
+    #embed "input.txt"
-    std::string line;
+};
-
-    while (std::getline(file, line)) {
 
+uint64_t num_stones(std::vector<uint64_t>& numbers, uint64_t blinks) {
+    std::unordered_map<uint64_t, uint64_t> nums = {};
+    for(auto num : numbers) {
+        nums[num] = 1;
     }
 
+    for(int i{0}; i < blinks; i++) {
+        std::unordered_map<uint64_t, uint64_t> new_nums = {};
+        for(auto &[num, count] : nums) {
+            if(num == 0) {
+                new_nums[1] += count;
+            } else if (std::to_string(num).length() % 2 == 0) {
+                std::string num_str = std::to_string(num);
+                uint64_t left = std::stoi(num_str.substr(0, num_str.length() / 2));
+                uint64_t right = std::stoi(num_str.substr(num_str.length() / 2));
+                new_nums[left] += count;
+                new_nums[right] += count;
+            } else {
+                uint64_t new_num = num * 2024;
+                new_nums[new_num] += count;
+            }
+        }
+        nums = new_nums;
+    }
+
+    uint64_t total = 0;
+    for(auto &[_, count] : nums) {
+        total += count;
+    }
+
+    return total;
+}
+
+uint64_t part_1() {
+    std::istringstream input_stream(content);
+    std::string line;
+    std::vector<uint64_t> numbers = {};
+
+    uint64_t curr_num;
+    while(input_stream >> curr_num) {
+        numbers.emplace_back(curr_num);
+    }
+
+    return num_stones(numbers, 25);
+}
+    
+uint64_t part_2() {
+    std::istringstream input_stream(content);
+    std::string line;
+    std::vector<uint64_t> numbers = {};
+
+    uint64_t curr_num;
+    while(input_stream >> curr_num) {
+        numbers.emplace_back(curr_num);
+    }
+    
+    return num_stones(numbers, 75);
+}
+
+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;
 }