(!****************************************************** Mosel Example Problems ====================== file k6queens.mos ````````````````` Placing N queens on an NxN chess board such that they do not attack each other. - Enumerating multiple solutions - (c) 2008 Fair Isaac Corporation author: S. Heipcke, Mar. 2002, rev. June 2011 *******************************************************!) model "K-6 Queens" uses "mmxprs" declarations NQ = 8 ! Number of rows and columns POS = 1..NQ queen: array(POS,POS) of mpvar ! 1 if queen at a position, 0 otherwise end-declarations ! Objective: total number of queens Total:= sum(r,c in POS) queen(r,c) ! Single queen per row and column forall(r in POS) sum(c in POS) queen(r,c) = 1 forall(c in POS) sum(r in POS) queen(r,c) = 1 ! Diagonals forall(c in POS) sum(r in c..NQ) queen(r-c+1,r) <= 1 forall(r in 2..NQ) sum(c in r..NQ) queen(c,c-r+1) <= 1 forall(c in POS) sum(r in 1..c) queen(r,c-r+1) <= 1 forall(r in 2..NQ) sum(c in r..NQ) queen(c,NQ-c+r) <= 1 forall(r,c in POS) queen(r,c) is_binary ! Solve the problem setparam("XPRS_enummaxsol", 100) ! Max. number of solutions to be saved minimize(XPRS_ENUM,Total) ! Solution printing forall(i in 1..getparam("XPRS_enumsols")) do selectsol(i) ! Select a solution from the pool writeln("Solution ", i, ". Total number of queens: ", getobjval) forall(r in POS) do forall(c in POS) write( if(getsol(queen(r,c))>0, "Q ", ". ") ) writeln end-do end-do end-model