Number of Unique Subjects Taught by Each Teacher — LeetCode 2356 Python Solution

Table: Teacher +-------------+------+ | Column Name | Type | +-------------+------+ | teacher_id | int | | subject_id | int | | dept_id | int | +-------------+------+ (subject_id, dept_id) is the primary key (combinations of columns with unique values) of this table. Each row in this table indicates that the teacher with teacher_id teaches the subject subject_id in the department dept_id.

+-------------+------+
| Column Name | Type |
+-------------+------+
| teacher_id  | int  |
| subject_id  | int  |
| dept_id     | int  |
+-------------+------+
(subject_id, dept_id) is the primary key (combinations of columns with unique values) of this table.
Each row in this table indicates that the teacher with teacher_id teaches the subject subject_id in the department dept_id.

import duckdb
import pandas as pd

def solution(teacher: pd.DataFrame) -> pd.DataFrame:
    con = duckdb.connect()
    con.register("Teacher", teacher)
    return con.execute("""SELECT teacher_id, COUNT(DISTINCT subject_id) AS cnt
FROM Teacher
GROUP BY 1;""").df()