aoc24/14/main.cc

#include <fstream>
#include <iostream>
#include <sstream>
#include <vector>
#include <tuple>
#include <set>

using namespace std;

#ifdef DEBUG
#define DBG(str) do { std::cout << str << std::endl; } while( false )
#else
#define DBG(str) do { } while ( false )
#endif

struct Point {
  int x;
  int y;
};

struct Guard {
  Point p;
  Point v;
};


vector<Guard> parseGuards(const char *path) {
  vector<Guard> guards;

  ifstream input(path);
  string line;

  while(getline(input, line)) {
    Guard guard;
    stringstream ss;
    char c;

    ss << line;

    ss >> c >> c >> guard.p.x >> c >> guard.p.y >> c >> c >> guard.v.x >> c >> guard.v.y;

    guards.push_back(guard);
  }

  return guards;
}

void printGuards(vector<Guard> guards) {
  for (auto guard : guards) {
    cout << "p=" << guard.p.x << "," << guard.p.y << " v=" << guard.v.x << "," << guard.v.y << endl; 
  }
}

void printField(vector<Guard> guards, int rows, int columns) {
  for (int y = 0; y < rows; y++) {
    for (int x = 0; x < columns; x++) {
      int num = 0;
      for (auto guard : guards) {
        if (guard.p.x == x && guard.p.y == y) num++;
      }
      if (num) cout << num;
      else     cout << '.';
    }
    cout << endl;
  }
  cout << endl;
}

// Function to perform Modular Addition
int modAdd(int a, int b, int m)
{
  // Adding m to handle negative numbers
  return ((a % m) + (b % m) + m) % m;
}


void doStep(vector<Guard> &guards, int rows, int columns) {
  for (auto &guard : guards) {
    guard.p.x = modAdd(guard.p.x, guard.v.x, columns);
    guard.p.y = modAdd(guard.p.y, guard.v.y, rows);
  }
}

long calculateResult(vector<Guard> guards, int rows, int columns) {
  long quadrants[4];

  int count = 0;
  for (int y = 0; y < rows / 2; y++) {
    for (int x = 0; x < columns / 2; x++) {
      for (auto guard : guards) {
        if (guard.p.x == x && guard.p.y == y) count++;
      }
    }
  }
  quadrants[0] = count;

  count = 0;
  for (int y = rows / 2 + 1; y < rows; y++) {
    for (int x = 0; x < columns / 2; x++) {
      for (auto guard : guards) {
        if (guard.p.x == x && guard.p.y == y) count++;
      }
    }
  }
  quadrants[1] = count;

  count = 0;
  for (int y = 0; y < rows / 2; y++) {
    for (int x = columns / 2 + 1; x < columns; x++) {
      for (auto guard : guards) {
        if (guard.p.x == x && guard.p.y == y) count++;
      }
    }
  }
  quadrants[2] = count;

  count = 0;
  for (int y = rows / 2 + 1; y < rows; y++) {
    for (int x = columns / 2 + 1; x < columns; x++) {
      for (auto guard : guards) {
        if (guard.p.x == x && guard.p.y == y) count++;
      }
    }
  }
  quadrants[3] = count;


  return quadrants[0] * quadrants[1] * quadrants[2] * quadrants[3];
}

long part1(const char *path, int rows, int columns) {
  vector<Guard> guards = parseGuards(path);

  // printField(guards, rows, columns);

  for (int i = 0; i < 100; i++) {
    doStep(guards, rows, columns);
  }

  // printField(guards, rows, columns);

  return calculateResult(guards, rows, columns);
}

bool isUnique(vector<Guard> guards, int rows, int columns) {
  for (int y = 0; y < rows; y++) {
    for (int x = 0; x < columns; x++) {
      bool flag = false;
      for (auto guard : guards) {
        if (guard.p.x == x && guard.p.y == y) {
          if (flag) return false;
          else flag = true;
        }
      }
    }
  }
  return true;
}

long part2(const char *path, int rows, int columns) {
  vector<Guard> guards = parseGuards(path);

  long step = 0;
  while (true) {
    if (isUnique(guards, rows, columns)) return step;

    doStep(guards, rows, columns);
    step++;
  }
}

int main(int argc, char *argv[]) {
  int example1 = part1("example", 7, 11);
  cout << "example1: " << example1 << endl;
  int input1 = part1("input", 103, 101);
  cout << "input1: " << input1 << endl;

  unsigned long long input2 = part2("input", 103, 101);
  cout << "input2: " << input2 << endl;
  return 0;
}