How hard is LeetCode 2388. Change Null Values in a Table to the Previous Value?

LeetCode 2388. Change Null Values in a Table to the Previous Value is rated Medium on LeetCode.

What topics does LeetCode 2388. Change Null Values in a Table to the Previous Value cover?

LeetCode 2388. Change Null Values in a Table to the Previous Value is tagged Database on LeetCode.

Change Null Values in a Table to the Previous Value — LeetCode 2388 Python Solution

MediumLeetCode PremiumDatabase

Problem: #2388
Reading time: 3 min
Source: leetcode.com

Table schema

SQL

Table: CoffeeShop +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | drink | varchar | +-------------+---------+ id is the primary key (column with unique values) for this table. Each row in this table shows the order id and the name of the drink ordered.

Example

SQL

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| drink       | varchar |
+-------------+---------+
id is the primary key (column with unique values) for this table.
Each row in this table shows the order id and the name of the drink ordered. Some drink rows are nulls.

Python solution

Python

import duckdb
import pandas as pd

def solution(coffee_shop: pd.DataFrame) -> pd.DataFrame:
    con = duckdb.connect()
    con.register("CoffeeShop", coffee_shop)
    return con.execute("""SELECT
    id,
    CASE
        WHEN drink IS NOT NULL THEN @cur := drink
        ELSE @cur
    END AS drink
FROM CoffeeShop;""").df()

Complexity

Measure	Complexity
Time	O(n log n) (typical)
Space	O(n) auxiliary

Frequently asked questions

How hard is LeetCode 2388. Change Null Values in a Table to the Previous Value?: LeetCode 2388. Change Null Values in a Table to the Previous Value is rated Medium on LeetCode.
What topics does LeetCode 2388. Change Null Values in a Table to the Previous Value cover?: LeetCode 2388. Change Null Values in a Table to the Previous Value is tagged Database on LeetCode.
Is LeetCode 2388. Change Null Values in a Table to the Previous Value a premium problem?: Yes. LeetCode 2388. Change Null Values in a Table to the Previous Value is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.