Mark constants as such.
Add a method that returns the list of valid locations for a given board.
Replace manual search with Board::ValidLocations().
Replace manual computation with Board::ValidLocations().
Replace manual search with Board::ValidLocations().
Remove redundant test.
Remove redundant test.
Replace manual search with Board::ValidLocations().
Replace manual search with Board::ValidLocations().
Replace manual searches with calls to Board::ValidLocations().
Rename Board::ValidLocations() to Board::locations().
Switch for vector<bool> to vector<char> for performance reasons.