02.cpp

#include <chrono>
#include <iostream>

struct pos {
  int row;
  int col;
};

int main() {
  auto tstart = std::chrono::high_resolution_clock::now();

  char kp1[3][3] = {
      {'1', '2', '3'},
      {'4', '5', '6'},
      {'7', '8', '9'},
  };
  char kp2[5][5] = {
      {0, 0, '1', 0, 0},          //
      {0, '2', '3', '4', 0},      //
      {'5', '6', '7', '8', '9'},  //
      {0, 'A', 'B', 'C', 0},      //
      {0, 0, 'D', 0, 0},          //
  };

  std::string input;
  int index = 0;

  struct pos pt1 = {1, 1};
  struct pos pt2 = {2, 0};
  char code_pt1[100];
  char code_pt2[100];
  while (std::getline(std::cin, input)) {
    for (char c : input) {
      switch (c) {
        case 'U':
          if (pt1.row > 0) {
            pt1.row -= 1;
          }
          if (pt2.row > 0 && kp2[pt2.row - 1][pt2.col] != 0) {
            pt2.row -= 1;
          }
          break;
        case 'R':
          if (pt1.col < 2) {
            pt1.col += 1;
          }
          if (pt2.col < 4 && kp2[pt2.row][pt2.col + 1] != 0) {
            pt2.col += 1;
          }
          break;
        case 'D':
          if (pt1.row < 2) {
            pt1.row += 1;
          }

          if (pt2.row < 4 && kp2[pt2.row + 1][pt2.col] != 0) {
            pt2.row += 1;
          }
          break;
        case 'L':
          if (pt1.col > 0) {
            pt1.col -= 1;
          }

          if (pt2.col > 0 && kp2[pt2.row][pt2.col - 1] != 0) {
            pt2.col -= 1;
          }
          break;
      }
    }

    code_pt1[index] = kp1[pt1.row][pt1.col];
    code_pt2[index] = kp2[pt2.row][pt2.col];
    index++;
  }
  code_pt1[index] = 0;
  code_pt2[index] = 0;

  std::cout << "--- Day 2: Bathroom Security ---\n";
  std::cout << "Part 1: " << code_pt1 << "\n";
  std::cout << "Part 2: " << code_pt2 << "\n";

  auto tstop = std::chrono::high_resolution_clock::now();
  auto duration =
      std::chrono::duration_cast<std::chrono::microseconds>(tstop - tstart);
  std::cout << "Time: " << duration.count() << " μs"
            << "\n";
  return EXIT_SUCCESS;
}