Data commit

Task/Cut-a-rectangle/Common-Lisp/cut-a-rectangle-1.lisp

@@ -0,0 +1,43 @@
+(defun cut-it (w h &optional (recur t))
+  (if (oddp (* w h)) (return-from cut-it 0))
+  (if (oddp h) (rotatef w h))
+  (if (= w 1) (return-from cut-it 1))
+
+  (let ((cnt 0)
+	(m (make-array (list (1+ h) (1+ w))
+		       :element-type 'bit
+		       :initial-element 0))
+	(cy (truncate h 2))
+	(cx (truncate w 2)))
+
+    (setf (aref m cy cx) 1)
+    (if (oddp w) (setf (aref m cy (1+ cx)) 1))
+
+    (labels
+      ((walk (y x turned)
+	     (when (or (= y 0) (= y h) (= x 0) (= x w))
+	       (incf cnt (if turned 2 1))
+	       (return-from walk))
+
+	     (setf (aref m y x) 1)
+	     (setf (aref m (- h y) (- w x)) 1)
+	     (loop for i from 0
+		   for (dy dx) in '((0 -1) (-1 0) (0 1) (1 0))
+		   while (or turned (< i 2)) do
+		   (let ((y2 (+ y dy))
+			 (x2 (+ x dx)))
+		     (when (zerop (aref m y2 x2))
+		       (walk y2 x2 (or turned (> i 0))))))
+	     (setf (aref m (- h y) (- w x)) 0)
+	     (setf (aref m y x) 0)))
+
+      (walk cy (1- cx) nil)
+      (cond ((= h w) (incf cnt cnt))
+	    ((oddp w) (walk (1- cy) cx t))
+	    (recur (incf cnt (cut-it h w nil))))
+    cnt)))
+
+(loop for w from 1 to 9 do
+      (loop for h from 1 to w do
+	    (if (evenp (* w h))
+	      (format t "~d x ~d: ~d~%" w h (cut-it w h)))))

Task/Cut-a-rectangle/Common-Lisp/cut-a-rectangle-2.lisp

@@ -0,0 +1,30 @@
+2 x 1: 2
+2 x 2: 2
+3 x 2: 3
+4 x 1: 4
+4 x 2: 4
+4 x 3: 9
+4 x 4: 22
+5 x 2: 5
+5 x 4: 39
+6 x 1: 6
+6 x 2: 6
+6 x 3: 23
+6 x 4: 90
+6 x 5: 263
+6 x 6: 1018
+7 x 2: 7
+7 x 4: 151
+7 x 6: 2947
+8 x 1: 8
+8 x 2: 8
+8 x 3: 53
+8 x 4: 340
+8 x 5: 1675
+8 x 6: 11174
+8 x 7: 55939
+8 x 8: 369050
+9 x 2: 9
+9 x 4: 553
+9 x 6: 31721
+9 x 8: 1812667