# 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*!).