2024 day3

src/2024/03/data/example.txt

@@ -0,0 +1 @@
+xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))

src/2024/03/data/example2.txt

@@ -0,0 +1 @@
+xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))

src/2024/03/makefile

@@ -0,0 +1 @@
+../../../tools/makefiles/compile/makefile

src/2024/03/src/lib

@@ -0,0 +1 @@
+../../../../src/lib

src/2024/03/src/main.cpp

@@ -0,0 +1,75 @@
+// adventofcode.com/2024/day/3
+
+#include <algorithm>
+#include <array>
+#include <numeric>
+#include <regex>
+#include <string>
+#include <string_view>
+#include <unordered_map>
+#include <vector>
+
+#include <fmt/core.h>
+
+#include "lib/io.h"
+#include "lib/parse.h"
+#include "lib/run.h"
+
+std::string readFile(const std::string& path) {
+  return read(path);
+}
+
+size_t parse(const std::string& path, bool dodont = false) {
+  auto data = readFile(path);
+
+  std::smatch match;
+  std::regex regex{R"(mul\(([0-9]+),([0-9]+)\)|do\(\)|don\'t\(\))"};
+
+  size_t result = 0;
+  bool enabled = true;
+
+  std::string::const_iterator start(data.cbegin());
+  while (std::regex_search(start, data.cend(), match, regex)) {
+    // fmt::println("match: '{}' '{}' '{}' ({})", std::string{match[0]}, std::string{match[1]},
+    //              std::string{match[2]}, match.size());
+
+    if (match.length(1) == 0 && match.length(2) == 0) {
+      if (dodont) {
+        if (match[0] == "do()") {
+          enabled = true;
+        } else if (match[0] == "don't()") {
+          enabled = false;
+        } else {
+          assert(false);
+        }
+      }
+    } else {
+      assert(match.size() == 3);
+      const auto num1 = to<size_t>(std::string{match[1]});
+      const auto num2 = to<size_t>(std::string{match[2]});
+      // fmt::println("match: {}, num1: {}, num2: {}", std::string{match[0]}, num1, num2);
+
+      if (enabled) {
+        result += (num1 * num2);
+      }
+    }
+    start = match.suffix().first;
+  }
+
+  return result;
+}
+
+size_t part1(const std::string& path) {
+  return parse(path);
+}
+
+size_t part2(const std::string& path) {
+  return parse(path, true);
+}
+
+int main() {
+  run(1, part1, true, 161UL);
+  run(1, part1, false, 178538786UL);
+  run(2, part2, true, 48UL, "data/example2.txt");
+  run(2, part2, false, 102467299UL);
+}

src/lib/io.cpp

@@ -1,10 +1,12 @@
 #include "lib/io.h"
 
+#include <filesystem>
 #include <fstream>
 
 #include <boost/algorithm/string.hpp>
 
 std::string read(const std::string& path, bool trim) {
+  assert(std::filesystem::exists(path));
   std::ifstream file{path};
 
   std::string data = {(std::istreambuf_iterator<char>(file)), std::istreambuf_iterator<char>()};