day_03a.cpp

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

int main() {
  std::ifstream file;
  file.open("../input/day_03_input");
  std::string row;
  std::vector<std::string> map;
  while (file >> row) {
    map.push_back(row);
  }

  const int n_rows = map.size();
  if (n_rows == 0) return 0;
  const int n_cols = map[0].size();
  const int inc_x = 3, inc_y = 1;
  int position_x = 0, position_y = 0;
  int n_tree = 0;

  while (position_y < n_rows) {
    if (map[position_y][position_x] == '#') {
      ++n_tree;
    }
    position_x += inc_x;
    position_x %= n_cols;
    position_y += inc_y;
  }
  std::cout << n_tree << '\n';
  return n_tree;
}