Standard ML of New Jersey, Version 110.0.3, January 30, 1998 [CM; autoload enabled]
- = [opening nqueens-test.sml]
[opening nqueens.sml]
signature QUEENS =
  sig
    type loc = int * int
    val solve : int -> loc list option
    val solve_all : int -> loc list list
  end
structure Queens : QUEENS
val print_board = fn : int -> (int * int) list -> unit
val print_solution = fn : (int * int) list option -> unit
val print_all_solutions = fn : (int * int) list list -> unit
val it = () : unit

Queens.solve: 1
Q 

Queens.solve: 2
There is no solution.

Queens.solve: 3
There is no solution.

Queens.solve: 4
. Q . . 
. . . Q 
Q . . . 
. . Q . 

Queens.solve: 5
Q . . . . 
. . Q . . 
. . . . Q 
. Q . . . 
. . . Q . 

Queens.solve: 6
. Q . . . . 
. . . Q . . 
. . . . . Q 
Q . . . . . 
. . Q . . . 
. . . . Q . 

Queens.solve: 7
Q . . . . . . 
. . Q . . . . 
. . . . Q . . 
. . . . . . Q 
. Q . . . . . 
. . . Q . . . 
. . . . . Q . 

Queens.solve_all: 4
Solution #1
. Q . . 
. . . Q 
Q . . . 
. . Q . 
Solution #2
. . Q . 
Q . . . 
. . . Q 
. Q . . 

Queens.solve_all: 5
Solution #1
Q . . . . 
. . Q . . 
. . . . Q 
. Q . . . 
. . . Q . 
Solution #2
Q . . . . 
. . . Q . 
. Q . . . 
. . . . Q 
. . Q . . 
Solution #3
. Q . . . 
. . . Q . 
Q . . . . 
. . Q . . 
. . . . Q 
Solution #4
. Q . . . 
. . . . Q 
. . Q . . 
Q . . . . 
. . . Q . 
Solution #5
. . Q . . 
Q . . . . 
. . . Q . 
. Q . . . 
. . . . Q 
Solution #6
. . Q . . 
. . . . Q 
. Q . . . 
. . . Q . 
Q . . . . 
Solution #7
. . . Q . 
Q . . . . 
. . Q . . 
. . . . Q 
. Q . . . 
Solution #8
. . . Q . 
. Q . . . 
. . . . Q 
. . Q . . 
Q . . . . 
Solution #9
. . . . Q 
. Q . . . 
. . . Q . 
Q . . . . 
. . Q . . 
Solution #10
. . . . Q 
. . Q . . 
Q . . . . 
. . . Q . 
. Q . . . 
val it = () : unit
val it = () : unit