Data commit

Task/Knapsack-problem-0-1/Icon/knapsack-problem-0-1.icon

@@ -0,0 +1,76 @@
+link printf
+
+global wants                    # items wanted for knapsack
+
+procedure main(A) # kanpsack 0-1
+   if !A == ("--trace"|"-t") then &trace := -1     # trace everything (debug)
+   if !A == ("--memoize"|"-m") then m :=: Memo_m   # hook (swap) procedure
+
+   printf("Knapsack-0-1: with maximum weight allowed=%d.\n",maxw  := 400)
+   showwanted(wants := get_wants())
+   showcontents(bag := m(*wants,maxw))
+   printf("Performance: time=%d ms collections=%d\n",&time,&collections)
+end
+
+record packing(items,weight,value)
+
+procedure Memo_m(i,w)           #: Hook procedure to memoize the knapsack
+static memoT
+initial memoT := table()
+   return \memoT[k := i||","||w] | ( memoT[k] := Memo_m(i,w) )
+end
+
+procedure m(i,w)                #: Solve the Knapsack 0-1 as per Wikipedia
+static nil
+initial nil := packing([],0,0)
+   if 0 = (i | w) then
+      return nil
+   else if wants[i].weight > w then
+           return m(i-1, w)
+        else {
+            x0 := m(i-1,w)
+            x1 := m(i-1,w-wants[i].weight)
+            if ( x1.value + wants[i].value) > x0.value then
+               return packing(x1.items ||| wants[i].items,
+                              x1.weight + wants[i].weight,
+                              x1.value + wants[i].value)
+            else
+               return x0
+        }
+end
+
+procedure showwanted(wants)     #: show the list of wanted items
+   every (tw := 0) +:= (!wants).weight
+   printf("Packing list has total weight=%d and includes %d items [",tw,*wants)
+   every printf(" %s",!(!wants).items|"]\n")
+end
+
+procedure showcontents(bag)     #: show the list of the packed bag
+   printf("The bag weighs=%d holding %d items [",bag.weight,*bag.items)
+   every printf(" %s",!bag.items|"]\n")
+end
+
+procedure get_wants()           #: setup list of wanted items
+   return  [ packing(["map"], 9, 150),
+             packing(["compass"], 13, 35),
+             packing(["water"], 153, 200),
+             packing(["sandwich"], 50, 160),
+             packing(["glucose"], 15, 60),
+             packing(["tin"], 68, 45),
+             packing(["banana"], 27, 60),
+             packing(["apple"], 39, 40),
+             packing(["cheese"], 23, 30),
+             packing(["beer"], 52, 10),
+             packing(["suntan cream"], 11, 70),
+             packing(["camera"], 32, 30),
+             packing(["T-shirt"], 24, 15),
+             packing(["trousers"], 48, 10),
+             packing(["umbrella"], 73, 40),
+             packing(["waterproof trousers"], 42, 70),
+             packing(["waterproof overclothes"], 43, 75),
+             packing(["note-case"], 22, 80),
+             packing(["sunglasses"], 7, 20),
+             packing(["towel"], 18, 12),
+             packing(["socks"], 4, 50),
+             packing(["book"], 30, 10) ]
+end