Inventory Management

Problem Statement

You are given two integer arrays:

• products, where products[i] represents the product ID being updated at step i

• changes, where changes[i] represents the stock change for that product:

  • positive value → stock added
  • negative value → stock removed

Return an integer array inventory_status of length n, where:

• inventory_status[i] is the highest stock quantity among all products after the i-th update
• If the inventory becomes empty, then inventory_status[i] = 0

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Function Signature

def inventoryManagement(products: List[int], changes: List[int]) -> List[int]:

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Input

• products: integer array of length n
• changes: integer array of length n

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Output

• Return an integer array inventory_status of length n

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Example 1

Input

products = [101, 104, 101, 105]
changes = [4, 2, -4, 3]

Output

[4, 4, 2, 3]

Explanation

• After update 0: Product 101 has 4 units → max stock = 4
• After update 1: Product 101 has 4, product 104 has 2 → max stock = 4
• After update 2: Product 101 removed completely, product 104 has 2 → max stock = 2
• After update 3: Product 105 has 3, product 104 has 2 → max stock = 3

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Example 2

Input

products = [150, 150, 120]
changes = [5, -5, 2]

Output

[5, 0, 2]

Explanation

• After update 0: Product 150 has 5 units → max stock = 5
• After update 1: Product 150 removed completely → inventory empty → 0
• After update 2: Product 120 has 2 units → max stock = 2

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Constraints

• The stock level of any product will never become negative.

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Efficient Approach Hint 🚀

Because n can be as large as 100,000, an efficient solution should use:

• HashMap / Dictionary → track stock of each product
• Max Heap / Counter optimization → quickly find current maximum stock

Target complexity:

• O(n log n) preferred
• O(n²) will timeout