Leetcode #2308: Arrange Table by Gender
In this guide, we solve Leetcode #2308 Arrange Table by Gender 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: Genders +-------------+---------+ | Column Name | Type | +-------------+---------+ | user_id | int | | gender | varchar | +-------------+---------+ user_id is the primary key (column with unique values) for this table. gender is ENUM (category) of type 'female', 'male', or 'other'.
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 |
+-------------+---------+
| user_id | int |
| gender | varchar |
+-------------+---------+
user_id is the primary key (column with unique values) for this table.
gender is ENUM (category) of type 'female', 'male', or 'other'.
Each row in this table contains the ID of a user and their gender.
The table has an equal number of 'female', 'male', and 'other'.
Python Solution
import duckdb
import pandas as pd
def solution(genders: pd.DataFrame) -> pd.DataFrame:
con = duckdb.connect()
con.register("Genders", genders)
return con.execute("""WITH
t AS (
SELECT
*,
RANK() OVER (
PARTITION BY gender
ORDER BY user_id
) AS rk1,
CASE
WHEN gender = 'female' THEN 0
WHEN gender = 'other' THEN 1
ELSE 2
END AS rk2
FROM Genders
)
SELECT user_id, gender
FROM t
ORDER BY rk1, rk2;""").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.