Primary Department for Each Employee — LeetCode 1789 Python Solution

EasyDatabase
Problem
#1789
Reading time
3 min

Table schema

SQL
Table: Employee +---------------+---------+ | Column Name | Type | +---------------+---------+ | employee_id | int | | department_id | int | | primary_flag | varchar | +---------------+---------+ (employee_id, department_id) is the primary key (combination of columns with unique values) for this table. employee_id is the id of the employee.

Example

SQL
+---------------+---------+
| Column Name   |  Type   |
+---------------+---------+
| employee_id   | int     |
| department_id | int     |
| primary_flag  | varchar |
+---------------+---------+
(employee_id, department_id) is the primary key (combination of columns with unique values) for this table.
employee_id is the id of the employee.
department_id is the id of the department to which the employee belongs.
primary_flag is an ENUM (category) of type ('Y', 'N'). If the flag is 'Y', the department is the primary department for the employee. If the flag is 'N', the department is not the primary.

Python solution

Python
import duckdb
import pandas as pd

def solution(employee: pd.DataFrame) -> pd.DataFrame:
    con = duckdb.connect()
    con.register("Employee", employee)
    return con.execute("""SELECT employee_id, department_id
FROM Employee
WHERE primary_flag = 'Y'
UNION
SELECT employee_id, department_id
FROM Employee
GROUP BY 1
HAVING COUNT(1) = 1;""").df()

Complexity

MeasureComplexity
TimeO(n log n) (typical)
SpaceO(n) auxiliary

Related problems

Frequently asked questions

How hard is LeetCode 1789. Primary Department for Each Employee?
LeetCode 1789. Primary Department for Each Employee is rated Easy on LeetCode.
What topics does LeetCode 1789. Primary Department for Each Employee cover?
LeetCode 1789. Primary Department for Each Employee is tagged Database on LeetCode.

Stuck on problems like this in a live interview?

Stealth Interview is a desktop app for macOS and Windows. It reads the problem off your screen and returns a working solution with a step-by-step explanation and its time and space complexity — invisible to screen sharing.

Get Stealth Interview