Day 3

d3/main.cxx

@@ -1,15 +1,56 @@
 #include <iostream>
-#include <fstream>
+#include <regex>
 
 using std::cout, std::endl;
 
-int main() {
+constexpr const char content[] = {
-    std::ifstream file{"../d3/input.txt"};
+    #embed "input.txt"
-    std::string line;
+};
 
-    while (std::getline(file, line)) {
+void part_1() {
+    std::string input = std::string(content);
 
+    auto acc{0};
+    std::regex re{"mul\\((\\d+),(\\d+)\\)"};
+    std::smatch match;
+
+    while (std::regex_search(input, match, re)) {
+        int a = std::stoi(match[1].str());
+        int b = std::stoi(match[2].str());
+        acc += a * b;
+
+        input = match.suffix().str(); 
     } 
 
+    cout << acc << endl;
+}
+
+void part_2() {
+    std::string input = std::string(content);
+
+    auto acc{0};
+    std::regex re{"do\\(\\)|don't\\(\\)|mul\\((\\d+),(\\d+)\\)"};
+    std::smatch match;
+    bool enabled{true};
+
+    while(std::regex_search(input, match, re)) {
+        if (match[0].str() == "do()") {
+            enabled = true;
+        } else if (match[0].str() == "don't()") {
+            enabled = false;
+        } else if (enabled) {
+                int x = std::stoi(match[1].str());
+                int y = std::stoi(match[2].str());
+                acc += x * y;
+        } 
+        input = match.suffix().str();
+    }
+    
+    cout << acc << endl;
+} 
+
+int main() {
+    part_1();
+    part_2();
     return 0;
 }