CareerCup

a 2 dimensional array can store where flags, etc. are. you can consider a 3 dimensional array as well - the third dimension can have the bomb/no bomb information as well as store a visible/flagged/hiding state.

you could also store two 2 dimension arrays i suppose, but that would take up more space.

2d array of square objects

square
{
    enum state={revealed,flagged,questioned,untouched};
    state my_state;
    int value; // -1 is a bomb, 0-8 represent number of neighboring bombs
}

I suppose you could describe more than that even:

class mineBoard
{
   class square
   {
        enum state{revealed,flagged,questioned,untouched};
        enum state my_state;
        int bomb_value;  // -1 for bomb, 0-8 for number of neighboring bombs
   };
   int width;
   int height;
   int num_bombs;
   square *board;
};