Sha256: d210dea6a7d9bda94d60eda1695b5430d0c3da714ddbaa08c84d44a5dd5fa741
Contents?: true
Size: 1.31 KB
Versions: 13
Compression:
Stored size: 1.31 KB
Contents
(define n-queens
{number --> symbol}
N -> (do (map (/. X (output "~A~%" X)) (n-queens-loop N (initialise N))) ok))
(define initialise
{number --> (list number)}
0 -> []
N -> [1 | (initialise (- N 1))])
(define n-queens-loop
{number --> (list number) --> [(list number)]}
N Config -> [] where (all_Ns? N Config)
N Config -> [Config | (n-queens-loop N (next_n N Config))]
where (and (ok_row? Config) (ok_diag? Config))
N Config -> (n-queens-loop N (next_n N Config)))
(define all_Ns?
{number --> (list number) --> boolean}
_ [] -> true
N [N | Ns] -> (all_Ns? N Ns)
_ _ -> false)
(define next_n
{number --> (list number) --> (list number)}
N [N | Ns] -> [1 | (next_n N Ns)]
_ [N | Ns] -> [(+ 1 N) | Ns])
(define ok_row?
{(list number) --> boolean}
[] -> true
[N | Ns] -> false where (element? N Ns)
[_ | Ns] -> (ok_row? Ns))
(define ok_diag?
{(list number) --> boolean}
[] -> true
[N | Ns] -> (and (ok_diag_N? (+ N 1) (- N 1) Ns)
(ok_diag? Ns)))
(define ok_diag_N?
{number --> number --> (list number) --> boolean}
_ _ [] -> true
Up Down [Up | _] -> false
Up Down [Down | _] -> false
Up Down [_ | Ns] -> (ok_diag_N? (+ 1 Up) (- Down 1) Ns))
Version data entries
13 entries across 13 versions & 1 rubygems