1 files changed, 69 insertions, 0 deletions
diff --git a/test/q.scm b/test/q.scm
new file mode 100644
index 0000000..498cfad
--- /dev/null
+++ b/test/q.scm
@@ -0,0 +1,69 @@
+(define (shl bits)
+  (define len (vector-length bits))
+  (define res (make-vector len))
+  (define (copy i)
+    (if (= i (- len 1))
+      #t
+      (and
+        (vector-set! res i
+                     (vector-ref bits (+ i 1)))
+        (copy (+ i 1)))))
+  (copy 0)
+  (set! copy '())
+  (vector-set! res (- len 1) #f)
+  res)
+
+(define (shr bits)
+  (define len (vector-length bits))
+  (define res (make-vector len))
+  (define (copy i)
+    (if (= i (- len 1))
+      #t
+      (and
+        (vector-set! res (+ i 1)
+                     (vector-ref bits i))
+        (copy (+ i 1)))))
+  (copy 0)
+  (set! copy '())
+  (vector-set! res 0 #f)
+  res)
+
+(define (empty-bits len) (make-vector len #f))
+(define vs vector-set!)
+(define vr vector-ref)
+(define res 0)
+(define (queen n)
+
+  (define (search l m r step)
+    (define (col-iter c)
+      (if (= c n)
+        #f
+        (and
+          (if (and (eq? (vr l c) #f)
+                   (eq? (vr r c) #f)
+                   (eq? (vr m c) #f))
+            (and
+              (vs l c #t)
+              (vs m c #t)
+              (vs r c #t)
+              ((lambda () (search l m r (+ step 1)) #t))
+              (vs l c #f)
+              (vs m c #f)
+              (vs r c #f))
+            )
+          (col-iter (+ c 1))
+          )))
+    (set! l (shl l))
+    (set! r (shr r))
+    (if (= step n)
+      (set! res (+ res 1))
+      (col-iter 0)))
+  ;  (set! col-iter '()))
+
+  (search (empty-bits n)
+          (empty-bits n)
+          (empty-bits n)
+          0)
+  res)
+
+(display (queen 8))