Algorithms: Inventory Update

Algorithms/inventoryUpdate.js

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+// https://www.freecodecamp.org/learn/coding-interview-prep/algorithms/inventory-update
+
+function updateInventory(arr1, arr2) {
+  const inventory = {};
+  arr1.forEach(([quantity, item]) => {
+    inventory[item] = quantity;
+  });
+  arr2.forEach(([quantity, item]) => {
+    if (inventory[item]) {
+      inventory[item] += quantity;
+    } else {
+      inventory[item] = quantity;
+    }
+  });
+  const inventoryArr = [];
+  for (const [item, quantity] of Object.entries(inventory)) {
+    inventoryArr.push([quantity, item]);
+  }
+  inventoryArr.sort(([quantityA, itemA], [quantityB, itemB]) =>
+    itemA > itemB ? 1 : -1
+  );
+  return inventoryArr;
+}
+
+console.log(
+  updateInventory(
+    [
+      [21, "Bowling Ball"],
+      [2, "Dirty Sock"],
+      [1, "Hair Pin"],
+      [5, "Microphone"],
+    ],
+    [
+      [2, "Hair Pin"],
+      [3, "Half-Eaten Apple"],
+      [67, "Bowling Ball"],
+      [7, "Toothpaste"],
+    ]
+  )
+);