day_12a.cpp

#include <fstream>
#include <iostream>
#include <vector>

int main() {
  std::ifstream file{"../input/day_12_input"};
  std::string com_inst;
  int dir = 0;
  int pos_x = 0;
  int pos_y = 0;
  while (std::getline(file, com_inst)) {
    char inst = com_inst[0];
    const int mag = std::stoi(com_inst.substr(1, com_inst.size() - 1));
    if (inst == 'F') {
      if (dir == 0)
        inst = 'E';
      else if (dir == 1)
        inst = 'N';
      else if (dir == 2)
        inst = 'W';
      else if (dir == 3)
        inst = 'S';
      else {
        std::cout << dir << " This should not happen" << '\n';
      }
    }

    if (inst == 'N') {
      pos_y += mag;
    } else if (inst == 'S') {
      pos_y -= mag;
    } else if (inst == 'E') {
      pos_x += mag;
    } else if (inst == 'W') {
      pos_x -= mag;
    } else if (inst == 'L') {
      dir += mag / 90;
      dir %= 4;
    } else if (inst == 'R') {
      dir -= mag / 90;
      dir += 4;
      dir %= 4;
    } else {
      std::cout << "This should also not happen" << '\n';
    }
  }
  std::cout << std::abs(pos_x) + std::abs(pos_y) << '\n';
  return 0;
}