Anonymous user
Sudoku: Difference between revisions
→{{header|Common Lisp}}
Line 152:
See e.g. [http://www.techfinesse.com/game/sudoku_solver.php this GPLed solver] written in C.
=={{header|Clojure}}==
<lang clojure>(ns sudoku
(:use [clojure.contrib.math :only (sqrt)]))
(defn print-grid [grid]
(doseq [y (range (count grid))]
(doseq [x (range (count grid))]
(print (retrieve grid x y) " "))
(println))
(println))
(defn retrieve [grid x y]
(get (get grid y) x))
(defn store [grid x y n]
(assoc grid y (assoc (get grid y) x n)))
(defn coordinates [grid x y]
(let [n (sqrt (count grid))
zx (* n (quot x n))
zy (* n (quot y n))]
(for [x (range zx (+ zx n)) y (range zy (+ zy n))]
[x y])))
(defn compatible? [grid x y n]
(or
(= n (retrieve grid x y))
(and
(zero? (retrieve grid x y))
(every? #(and (not= n (retrieve grid % y)) (not= n (retrieve grid x %))) (range (count grid)))
(every? #(not= n (retrieve grid (first %) (second %))) (coordinates grid x y)))))
(defn solve [grid x y]
(let [m (count grid)]
(if (= y m)
(print-grid grid)
(doseq [n (range 1 (inc m))]
(when (compatible? grid x y n)
(let [new-grid (store grid x y n)]
(if (= x (dec m))
(solve new-grid 0 (inc y))
(solve new-grid (inc x) y))))))))
</lang>
<lang clojure>sudoku> (solve [[3 9 4 0 0 2 6 7 0]
[0 0 0 3 0 0 4 0 0]
[5 0 0 6 9 0 0 2 0]
[0 4 5 0 0 0 9 0 0]
[6 0 0 0 0 0 0 0 7]
[0 0 7 0 0 0 5 8 0]
[0 1 0 0 6 7 0 0 8]
[0 0 9 0 0 8 0 0 0]
[0 2 6 4 0 0 7 3 5]]
0 0)
3 9 4 8 5 2 6 7 1
2 6 8 3 7 1 4 5 9
5 7 1 6 9 4 8 2 3
1 4 5 7 8 3 9 6 2
6 8 2 9 4 5 3 1 7
9 3 7 1 2 6 5 8 4
4 1 3 5 6 7 2 9 8
7 5 9 2 3 8 1 4 6
8 2 6 4 1 9 7 3 5
nil
</lang>
=={{header|Common Lisp}}==
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