(!**************************************************************** Mosel Example Problems ====================== file k6queens_ka.mos ```````````````````` Placing N queens on an NxN chess board such that they do not attack each other. (c) 2008 Fair Isaac Corporation author: S. Heipcke, March 2005, Sep. 2017 *****************************************************************!) model nqueen uses "kalis","mmsvg" parameters N = 10 ! Number of queens SOL = 10 ! Number of solutions end-parameters forward procedure print_solution(numsol: integer) forward procedure draw_solution(numsol: integer) declarations ROWS = 1..N ! Rows and columns queen: array(ROWS) of cpvar ! Position of queen per row end-declarations ! Defining the decision variables forall(i in ROWS) do 1 <= queen(i); queen(i) <= N end-do ! One queen per column all_different(queen,KALIS_GEN_ARC_CONSISTENCY) ! No two queens on the same diagonal forall(i in ROWS, j in i+1..N) do queen(i) <> queen(j) queen(i) <> queen(j) + j - i queen(j) <> queen(i) + j - i end-do ! Setting enumeration parameters cp_set_branching(assign_var(KALIS_SMALLEST_DOMAIN, KALIS_RANDOM_VALUE, queen)) ! Solve the problem (generate up to SOL solutions) solct:= 0; svgrefresh while (cp_find_next_sol and solct<SOL and not svgclosing) do solct+=1 print_solution(solct) draw_solution(solct) cp_show_stats end-do svgwaitclose("Close browser window to terminate model execution.", 1) !**************************************************************** ! **** Solution printing **** procedure print_solution(numsol: integer) writeln("Solution ", numsol) ct:=4 write(" 1 ") while(ct<=N) do write(strfmt(ct,-4)) ct+=4 end-do writeln forall(r in ROWS) do write(strfmt(r,3), " ") forall(c in ROWS) write(if(c=getsol(queen(r)), "Q", ".")) writeln end-do writeln("Positions: ", queen) end-procedure ! **** Solution drawing in SVG format **** procedure draw_solution(numsol: integer) svgerase ! Delete previous graph svgaddgroup("S", "Solution "+numsol) forall(r in ROWS) do sol:= getsol(queen(r)) forall(c in ROWS | c=sol) svgaddtext(r,c,"Q") end-do ! Draw the board svgaddgroup("B", "", SVG_BLACK) forall(i in 1..N+1) svgaddline(i-0.5, 0.5, i-0.5, N+0,5) forall(j in 1..N+1) svgaddline(0.5, j-0.5, N+0.5, j-0,5) svgsetgraphscale(20) svgrefresh ! Uncomment next line to pause at every iteration: svgpause end-procedure end-model