Solution.cpp

class Solution {
public:
    void gameOfLife(vector<vector<int>>& board) {
        int m = board.size(), n = board[0].size();
        vector<vector<int>> dirs = {{0, 1}, {0, - 1}, {1, 0}, {-1, 0}, {1, 1}, {1, -1}, {-1, 1}, {-1, -1}};
        for (int i = 0; i < m; ++i)
        {
            for (int j = 0; j < n; ++j)
            {
                int cnt = 0;
                for (auto& dir : dirs)
                {
                    int x = i + dir[0], y = j + dir[1];
                    if (x >= 0 && x < m && y >= 0 && y < n && (board[x][y] == 1 || board[x][y] == 2)) ++cnt;
                }
                if (board[i][j] == 1 && (cnt < 2 || cnt > 3)) board[i][j] = 2;
                else if (board[i][j] == 0 && cnt == 3) board[i][j] = 3;
            }
        }
        for (int i = 0; i < m; ++i)
            for (int j = 0; j < n; ++j)
                board[i][j] %= 2;
    }
};