Just another update

Task/Sudoku/Clojure/sudoku-1.clj

@@ -1,41 +1,24 @@
-(ns sudoku
-  (:use [clojure.contrib.math :only (sqrt)]))
+(ns rosettacode.sudoku
+  (:use [clojure.pprint :only (cl-format)]))
 
-(defn print-grid [grid]
-  (doseq [y (range (count grid))]
-    (doseq [x (range (count grid))]
-      (print (retrieve grid x y) " "))
-    (println))
-  (println))
+(defn- compatible? [m x y n]
+  (let [n= #(= n (get-in m [%1 %2]))]
+    (or (n= y x)
+      (let [c (count m)]
+        (and (zero? (get-in m [y x]))
+             (not-any? #(or (n= y %) (n= % x)) (range c))
+             (let [zx (* c (quot x c)), zy (* c (quot y c))]
+               (every? false?
+                 (map n= (range zy (+ zy c)) (range zx (+ zx c))))))))))
 
-(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))))))))
+(defn solve [m]
+  (let [c (count m)]
+    (loop [m m, x 0, y 0]
+      (if (= y c) m
+        (let [ng (->> (range 1 c)
+                      (filter #(compatible? m x y %))
+                      first
+                      (assoc-in m [y x]))]
+          (if (= x (dec c))
+            (recur ng 0 (inc y))
+            (recur ng (inc x) y)))))))

Task/Sudoku/Clojure/sudoku-2.clj

@@ -1,13 +1,13 @@
-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)
+sudoku>(cl-format true "~{~{~a~^ ~}~%~}"
+ (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]])
 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