How do you solve Sales Analysis III on LeetCode?

Sales Analysis III (LeetCode #1084) 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 the date range and ensuring all sales fall within it is crucial.

What is the brute force solution for Sales Analysis III?

The brute force approach for Sales Analysis III is Brute Force, with O(n²) time complexity and O(1) space complexity. In this approach, we will check each product to see if it was sold in the specified date range. If a product is sold outside of this range, we discard it. This is straightforward but inefficient. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Sales Analysis III?

Sales Analysis III uses the following concepts: Database. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Sales Analysis III?

Always clarify the problem requirements, especially around date ranges. Think about how to efficiently filter and group data in SQL. Practice writing SQL queries on paper or in a SQL environment to build confidence.

What are common mistakes when solving Sales Analysis III?

Not considering sales that occur outside the specified date range. Failing to use GROUP BY and HAVING correctly to filter results.

#1084

Sales Analysis III

Easy

DatabaseHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

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Intuition

Time O(n)Space O(n)

In this approach, we will use a single query to filter products based on sales that occurred only in the specified date range. This is more efficient as it avoids unnecessary checks.

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Algorithm

3 steps

1Step 1: Select products from the Product table that have sales in the Sales table.
2Step 2: Group the results by product_id and ensure that all sales for each product fall within the date range.
3Step 3: Use a HAVING clause to filter out products that have sales outside the specified date range.

solution.py5 lines

1SELECT p.product_id, p.product_name
2FROM Product p
3JOIN Sales s ON p.product_id = s.product_id
4GROUP BY p.product_id, p.product_name
5HAVING MIN(s.sale_date) >= '2019-01-01' AND MAX(s.sale_date) <= '2019-03-31';

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Complexity note: This complexity is efficient because we are using a single scan through the sales data and grouping it, rather than checking each product against all sales.

1Understanding the date range and ensuring all sales fall within it is crucial.
2Using aggregation functions like MIN and MAX can simplify checks for conditions across groups.

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