How do you solve Product Price at a Given Date on LeetCode?

Product Price at a Given Date (LeetCode #1164) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(n) space complexity. Key insight: Understanding how to handle date comparisons is crucial.

What is the time complexity of Product Price at a Given Date?

The optimal solution for Product Price at a Given Date runs in O(n) time and uses O(n) space. The complexity is linear because we only need to traverse the list of products once, storing results in a dictionary.

What is the brute force solution for Product Price at a Given Date?

The brute force approach for Product Price at a Given Date is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach checks each product's price change history to find the most recent price before the given date. This is straightforward but inefficient as it may require multiple scans of the data. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Product Price at a Given Date?

Product Price at a Given Date uses the following concepts: Database. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Product Price at a Given Date?

Clarify the problem requirements, especially regarding default values. Think about edge cases, such as no price changes for a product. Discuss your thought process and approach before jumping into coding.

What are common mistakes when solving Product Price at a Given Date?

Not considering the default price when there are no changes. Failing to account for multiple changes on the same date.

#1164

Product Price at a Given Date

Medium

DatabaseHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(n)

💡

Intuition

Time O(n)Space O(n)

By using a single pass through the data and storing the latest price for each product in a dictionary, we can efficiently determine the price on the specified date without redundant checks.

⚙️

Algorithm

3 steps

1Step 1: Create a dictionary to hold the latest price for each product.
2Step 2: Iterate through the Products table, updating the dictionary with the new price if the change_date is on or before the specified date.
3Step 3: For each product in the dictionary, if it has no price set, default to 10.

solution.py6 lines

1SELECT product_id, COALESCE(price, 10) AS price
2FROM (SELECT product_id, new_price AS price
3FROM Products
4WHERE change_date <= '2019-08-16'
5ORDER BY change_date DESC) AS latest_prices
6GROUP BY product_id;

ℹ

Complexity note: The complexity is linear because we only need to traverse the list of products once, storing results in a dictionary.

1Understanding how to handle date comparisons is crucial.
2Using a dictionary can significantly reduce the number of operations needed.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.