Leetcode #2922: Market Analysis III
In this guide, we solve Leetcode #2922 Market Analysis III in Python and focus on the core idea that makes the solution efficient.
You will see the intuition, the step-by-step method, and a clean Python implementation you can use in interviews.
Problem Statement
Table: Users +----------------+---------+ | Column Name | Type | +----------------+---------+ | seller_id | int | | join_date | date | | favorite_brand | varchar | +----------------+---------+ seller_id is column of unique values for this table. This table contains seller id, join date, and favorite brand of sellers.
Quick Facts
- Difficulty: Medium
- Premium: Yes
- Tags: Database
Intuition
The task is relational in nature, which maps cleanly to DataFrame operations in Python.
By treating tables as DataFrames, joins and group-bys become concise and readable.
Approach
Load the inputs as DataFrames and apply the appropriate merge, filter, or group-by.
Select or rename the columns to match the required output.
Steps:
- Load inputs as DataFrames.
- Apply merge/groupby/filter operations.
- Select the output columns.
Example
+----------------+---------+
| Column Name | Type |
+----------------+---------+
| seller_id | int |
| join_date | date |
| favorite_brand | varchar |
+----------------+---------+
seller_id is column of unique values for this table.
This table contains seller id, join date, and favorite brand of sellers.
Python Solution
import duckdb
import pandas as pd
def solution(users: pd.DataFrame, items: pd.DataFrame, orders: pd.DataFrame) -> pd.DataFrame:
con = duckdb.connect()
con.register("Users", users)
con.register("Items", items)
con.register("Orders", orders)
return con.execute("""WITH
T AS (
SELECT seller_id, COUNT(DISTINCT item_id) AS num_items
FROM
Orders
JOIN Users USING (seller_id)
JOIN Items USING (item_id)
WHERE item_brand != favorite_brand
GROUP BY 1
)
SELECT seller_id, num_items
FROM T
WHERE num_items = (SELECT MAX(num_items) FROM T)
ORDER BY 1;""").df()
Complexity
The time complexity is O(n log n) (typical). The space complexity is O(n).
Edge Cases and Pitfalls
Watch for boundary values, empty inputs, and duplicate values where applicable. If the problem involves ordering or constraints, confirm the invariant is preserved at every step.
Summary
This Python solution focuses on the essential structure of the problem and keeps the implementation interview-friendly while meeting the constraints.