Two types of pieces, bishops and rooks, are to be placed on a 10×10 chessboard (without necessarily filling it) such that each piece occupies exactly one square of the board. A bishop B is said to attack a piece P if B and P are on the same diagonal and there are no pieces between B and P on that diagonal; a rook R is said to attack a piece P if R and P are on the same row or column and there are no pieces between R and P on that row or column.
A piece P is chocolate if no other piece Q attacks P.
What is the maximum number of chocolate pieces there may be, after placing some pieces on the chessboard?Proposed by José Alejandro Reyes González MexicocombinatoricsChessboardboardChess rookBishop