Leetcode #1747: Leetflex Banned Accounts
In this guide, we solve Leetcode #1747 Leetflex Banned Accounts 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: LogInfo +-------------+----------+ | Column Name | Type | +-------------+----------+ | account_id | int | | ip_address | int | | login | datetime | | logout | datetime | +-------------+----------+ This table may contain duplicate rows. The table contains information about the login and logout dates of Leetflex accounts.
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 |
+-------------+----------+
| account_id | int |
| ip_address | int |
| login | datetime |
| logout | datetime |
+-------------+----------+
This table may contain duplicate rows.
The table contains information about the login and logout dates of Leetflex accounts. It also contains the IP address from which the account was logged in and out.
It is guaranteed that the logout time is after the login time.
Python Solution
import duckdb
import pandas as pd
def solution(log_info: pd.DataFrame) -> pd.DataFrame:
con = duckdb.connect()
con.register("LogInfo", log_info)
return con.execute("""SELECT DISTINCT
a.account_id
FROM
LogInfo AS a
JOIN LogInfo AS b
ON a.account_id = b.account_id
AND a.ip_address != b.ip_address
AND a.login BETWEEN b.login AND b.logout;""").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.