Initial data commit

Task/Knapsack-problem-Bounded/Common-Lisp/knapsack-problem-bounded.lisp

@@ -0,0 +1,34 @@
+;;; memoize
+(defmacro mm-set (p v) `(if ,p ,p (setf ,p ,v)))
+
+(defun knapsack (max-weight items)
+  (let ((cache (make-array (list (1+ max-weight) (1+ (length items)))
+			   :initial-element nil)))
+
+    (labels ((knapsack1 (spc items)
+	(if (not items) (return-from knapsack1 (list 0 0 '())))
+	 (mm-set (aref cache spc (length items))
+	   (let* ((i (first items))
+		  (w (second i))
+		  (v (third i))
+		  (x (knapsack1 spc (cdr items))))
+	     (loop for cnt from 1 to (fourth i) do
+		   (let ((w (* cnt w)) (v (* cnt v)))
+		     (if (>= spc w)
+		       (let ((y (knapsack1 (- spc w) (cdr items))))
+			 (if (> (+ (first y) v) (first x))
+			   (setf x (list (+ (first  y) v)
+					 (+ (second y) w)
+					 (cons (list (first i) cnt) (third y)))))))))
+	     x))))
+
+      (knapsack1 max-weight items))))
+
+(print
+  (knapsack 400
+	    '((map 9 150 1) (compass 13 35 1) (water 153 200 2) (sandwich 50 60 2)
+              (glucose 15 60 2) (tin 68 45 3) (banana 27 60 3) (apple 39 40 3)
+	      (cheese 23 30 1) (beer 52 10 3) (cream 11 70 1) (camera 32 30 1)
+	      (T-shirt 24 15 2) (trousers 48 10 2) (umbrella 73 40 1)
+	      (trousers 42 70 1) (overclothes 43 75 1) (notecase 22 80 1)
+	      (glasses 7 20 1) (towel 18 12 2) (socks 4 50 1) (book 30 10 2))))