[HackerRank] The Bomberman Game

// 상하좌우
IntPair dir[]
{
	{ 1, 0 },
	{-1, 0 },
	{ 0, -1 },
	{ 0, 1 }
};

vector<string> bomberMan(int n, vector<string> grid)
{
	vector<pair<int, int>> pos;
	int r = grid.size(), c = grid[r - 1].size();

	if (0 == n % 2)
	{
		for (int y = 0; y < grid.size(); ++y)
			for (int x = 0; x < grid[y].size(); ++x)
				grid[y][x] = 'O';

		return grid;
	}
	else if ((n + 1) % 4 == 0)
		n = 3;

	else if (n != 1 && (n - 1) % 4 == 0)
		n = 5;
	
	for (int t = 2; t <= n; ++t)
	{
		if (0 == t % 2)
		{
			for (int y = 0; y < grid.size(); ++y)
			{
				for (int x = 0; x < grid[y].size(); ++x)
				{
					if (grid[y][x] == 'O')
						pos.push_back({ y, x });

					else
						grid[y][x] = 'O';
				}
			}
		}
		else
		{
			for (int i = 0; i < pos.size(); ++i)
			{
				int y = pos[i].first, x = pos[i].second;
				grid[y][x] = '.';

				for (int i = 0; i < 4; i++)
				{
					int ny = y + dir[i].first, nx = x + dir[i].second;

					if (ny >= 0 &&
						ny < r)
						grid[ny][x] = '.';

					if (nx >= 0 &&
						nx < c)
						grid[y][nx] = '.';
				}
			}
			pos.clear();
		}
	}
	return grid;
}