A

David

Darling

rooks problem

The rooks problem is to find the maximum number of chess rooks that can be placed on an n × n chessboard such that no rook attacks another. Since each rook attacks all squares in the rank and file upon which it rests, this number is n: the rooks may be placed along the diagonal. The total number of ways of placing n non-attacking rooks is n factorial (n!).