A-M baby

Task/Knapsack-problem-Unbounded/Go/knapsack-problem-unbounded.go

@@ -0,0 +1,70 @@
+package main
+
+import "fmt"
+
+type Item struct {
+    Name           string
+    Value          int
+    Weight, Volume float64
+}
+
+type Result struct {
+    Counts []int
+    Sum    int
+}
+
+func min(a, b int) int {
+    if a < b {
+        return a
+    }
+    return b
+}
+
+func Knapsack(items []Item, index int, weight, volume float64) (best *Result) {
+    if index == len(items) {
+        return &Result{make([]int, len(items)), 0}
+    }
+    itemValue := items[index].Value
+    itemWeight := items[index].Weight
+    itemVolume := items[index].Volume
+    maxCount := min(int(weight/itemWeight), int(volume/itemVolume))
+    for count := 0; count <= maxCount; count++ {
+        sol := Knapsack(items, index+1,
+            weight-float64(count)*itemWeight,
+            volume-float64(count)*itemVolume)
+        if sol != nil {
+            sol.Counts[index] = count
+            sol.Sum += itemValue * count
+            if best == nil || sol.Sum > best.Sum {
+                best = sol
+            }
+        }
+    }
+    return
+}
+
+func main() {
+    items := []Item{
+        Item{"Panacea", 3000, 0.3, 0.025},
+        Item{"Ichor",   1800, 0.2, 0.015},
+        Item{"Gold",    2500, 2.0, 0.002},
+    }
+    var sumCount, sumValue int
+    var sumWeight, sumVolume float64
+
+    result := Knapsack(items, 0, 25, 0.25)
+
+    for i := range result.Counts {
+        fmt.Printf("%-8s x%3d  -> Weight: %4.1f  Volume: %5.3f  Value: %6d\n",
+            items[i].Name, result.Counts[i], items[i].Weight*float64(result.Counts[i]),
+            items[i].Volume*float64(result.Counts[i]), items[i].Value*result.Counts[i])
+
+        sumCount += result.Counts[i]
+        sumValue += items[i].Value * result.Counts[i]
+        sumWeight += items[i].Weight * float64(result.Counts[i])
+        sumVolume += items[i].Volume * float64(result.Counts[i])
+    }
+
+    fmt.Printf("TOTAL (%3d items) Weight: %4.1f  Volume: %5.3f  Value: %6d\n",
+        sumCount, sumWeight, sumVolume, sumValue)
+}