Advent-of-Code/2024/4/main.cpp

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

int main()
{
	const std::string filename = "data.txt";
	std::ifstream ifs(filename);
	if(!ifs.is_open())
	{
		std::cerr << "Missing " << filename << "." << std::endl;
		return -1;
	}

	unsigned long total = 0;
	unsigned long total_pt2 = 0;

	std::vector<std::vector<char>> game;

	for(std::string line; std::getline(ifs, line); )
	{
		if(line == "")
			continue;

		// Add new row to fill out:
		game.push_back({});

		// for each value in the line:
		for(const char &c : line)
		{
			// Fill out the row:
			game.back().push_back(c);
		}
	}

	// DEBUG:
	// for(auto row : game)
	// {
	// 	for(auto c : row)
	// 		std::cout << c;
	// 	std::cout << std::endl;
	// }

	for(int y = 0; y < game.size(); ++y)
	{
		for(int x = 0; x < game[y].size(); ++x)
		{
			// right:
			if(x + 3 < game[y].size())
			{
				if(game[y][x] == 'X' &&
				   game[y][x+1] == 'M' &&
				   game[y][x+2] == 'A' &&
				   game[y][x+3] == 'S')
					++total;
			}

			// down right:
			if(x + 3 < game[y].size() &&
			   y + 3 < game.size())
			{
				if(game[y][x] == 'X' &&
				   game[y+1][x+1] == 'M' &&
				   game[y+2][x+2] == 'A' &&
				   game[y+3][x+3] == 'S')
					++total;
			}

			// down:
			if(y + 3 < game.size())
			{
				if(game[y][x] == 'X' &&
				   game[y+1][x] == 'M' &&
				   game[y+2][x] == 'A' &&
				   game[y+3][x] == 'S')
					++total;
			}

			// down left:
			if(x - 3 >= 0 &&
			   y + 3 < game.size())
			{
				if(game[y][x] == 'X' &&
				   game[y+1][x-1] == 'M' &&
				   game[y+2][x-2] == 'A' &&
				   game[y+3][x-3] == 'S')
					++total;
			}

			// left:
			if(x - 3 >= 0)
			{
				if(game[y][x] == 'X' &&
				   game[y][x-1] == 'M' &&
				   game[y][x-2] == 'A' &&
				   game[y][x-3] == 'S')
					++total;
			}

			// up left:
			if(x - 3 >= 0 &&
			   y - 3 >= 0)
			{
				if(game[y][x] == 'X' &&
				   game[y-1][x-1] == 'M' &&
				   game[y-2][x-2] == 'A' &&
				   game[y-3][x-3] == 'S')
					++total;
			}

			// up:
			if(y - 3 >= 0)
			{
				if(game[y][x] == 'X' &&
				   game[y-1][x] == 'M' &&
				   game[y-2][x] == 'A' &&
				   game[y-3][x] == 'S')
					++total;
			}

			// up right:
			if(x + 3 < game[y].size() &&
			   y - 3 >= 0)
			{
				if(game[y][x] == 'X' &&
				   game[y-1][x+1] == 'M' &&
				   game[y-2][x+2] == 'A' &&
				   game[y-3][x+3] == 'S')
					++total;
			}
		}
	}

	for(int y = 1; y < game.size() - 1; ++y)
	{
		for(int x = 1; x < game[y].size() - 1; ++x)
		{
			if(game[y][x] != 'A')
				continue;

			int good = 0;
			// top left to bottom right
			if((game[y-1][x-1] == 'M' &&
			    game[y+1][x+1] == 'S')
			   ||
			   (game[y-1][x-1] == 'S' &&
			    game[y+1][x+1] == 'M'))
				++good;
			// top right to bottom left
			if((game[y-1][x+1] == 'M' &&
			    game[y+1][x-1] == 'S')
			   ||
			   (game[y-1][x+1] == 'S' &&
			    game[y+1][x-1] == 'M'))
				++good;

			if(good == 2)
				++total_pt2;
		}
	}

	std::cout << "    Total: " <<     total << std::endl;
	std::cout << "PT2 Total: " << total_pt2 << std::endl;

	return 0;
}