Knapsack problem

Author: edignot

src/bitwise-operator-permissions/bitwise-operator-permissions.js

@@ -0,0 +1,49 @@
+// Problem: Given a set of items, each with a weight and a value, determine the number of each item to include in a collection so that the total weight is less than or equal to a given limit and the total value is as large as possible
+// Time complexity:
+
+const items = [
+    { id: "a", weight: 8, value: 7 },
+    { id: "b", weight: 4, value: 5 },
+    { id: "c", weight: 2, value: 3 },
+    { id: "d", weight: 7, value: 5 },
+];
+const maxWeight = 11;
+
+const getBag = (items, maxWeight, itemIndex) => {
+    if (maxWeight === 0 || itemIndex < 0) {
+        return {
+            items: [],
+            value: 0,
+            weight: 0,
+        };
+    }
+
+    if (maxWeight < items[itemIndex].weight) {
+        return getBag(items, maxWeight, itemIndex - 1);
+    }
+
+    const bagWithItem =
+        itemIndex &&
+        getBag(items, maxWeight - items[itemIndex].weight, itemIndex - 1);
+
+    const bagWithoutItem =
+        itemIndex &&
+        getBag(items, maxWeight - items[itemIndex].weight, itemIndex - 1);
+
+    const valueWithItem = bagWithItem.value + items[itemIndex].value;
+
+    const valueWithoutItem = bagWithoutItem.value;
+
+    if (valueWithItem > valueWithoutItem) {
+        const updatedBag = {
+            items: bagWithItem.items.concat(items[itemIndex]),
+            value: (bagWithItem.value += items[itemIndex].value),
+            weight: (bagWithItem.weight += items[itemIndex].weight),
+        };
+        return updatedBag;
+    } else {
+        return bagWithoutItem;
+    }
+};
+
+export default getBag;

src/bitwise-operator-permissions/bitwise-operator-permissions.test.js

@@ -0,0 +1,24 @@
+import getBag from "./knapsack";
+
+describe("Knapsack", () => {
+    test("Knapsack one", () => {
+        const items = [
+            { id: "a", weight: 8, value: 7 },
+            { id: "b", weight: 4, value: 5 },
+            { id: "c", weight: 2, value: 3 },
+            { id: "d", weight: 7, value: 5 },
+        ];
+        const maxWeight = 11;
+        const result = {
+            items: [
+                { id: "c", value: 3, weight: 2 },
+                { id: "d", value: 5, weight: 7 },
+            ],
+            value: 8,
+            weight: 9,
+        };
+        expect(getBag(items, maxWeight, items.length - 1)).toStrictEqual(
+            result
+        );
+    });
+});

src/kanpsack/knapsack.js

@@ -11,7 +11,7 @@ export const isPowerOfTwo = (num) => {
 // Utilizing bitwise operators
 // Binary number: 128 64 32 16 8 4 2 1
 // Converting number to binary number - using subtractions 75 -> 01001011
+// Time complexity: O(1)
 export const isPowerOfTwoBitwise = (num) => {
     return num & (num - 1) ? false : true;
 };
-