first three days

day1/src/main.cpp

@@ -0,0 +1,71 @@
+#include <fstream>
+#include <iostream>
+#include <vector>
+
+struct Instruction {
+  const char direction;
+  const int value;
+};
+
+std::vector<Instruction> parse_input_file(const std::string &path) {
+  std::ifstream file;
+  std::vector<Instruction> vec;
+  std::string line;
+
+  file.open(path);
+  if (file.is_open()) {
+    while (std::getline(file, line)) {
+      auto instr = line.at(0);
+      int value = std::stoi(line.substr(1));
+      vec.emplace_back(Instruction{instr, value});
+    }
+    file.close();
+  } else {
+    std::cout << "Failed to open file: " << path << std::endl;
+  }
+
+  return vec;
+}
+
+std::tuple<int, int> doit(const std::vector<Instruction> &instructions) {
+  int dial_val = 50;
+  int zero_counter_part1 = 0;
+  int zero_counter_part2 = 0;
+  for (const auto &instr : instructions) {
+    for (int i = 0; i < instr.value; i++) {
+      if (instr.direction == 'L') {
+        dial_val--;
+      } else {
+        dial_val++;
+      }
+
+      if (dial_val > 99)
+        dial_val = 0;
+      else if (dial_val < 0)
+        dial_val = 99;
+      if (dial_val == 0)
+        zero_counter_part2 += 1;
+    }
+    if (dial_val == 0)
+      zero_counter_part1 += 1;
+
+    std::cout << "dial_val: " << dial_val << std::endl;
+  }
+  return std::make_tuple(zero_counter_part1, zero_counter_part2);
+}
+
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    std::cout << "One argument required: input txt" << std::endl;
+  }
+
+  auto instructions = parse_input_file(argv[1]);
+
+  auto num_zeros = doit(instructions);
+
+  std::cout << "Number of times dial hits zero (part 1): "
+            << std::get<0>(num_zeros) << std::endl;
+  std::cout << "Number of times dial hits zero (part 2): "
+            << std::get<1>(num_zeros) << std::endl;
+  return 0;
+}