Leetcode #1174: Immediate Food Delivery II
In this guide, we solve Leetcode #1174 Immediate Food Delivery II 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: Delivery +-----------------------------+---------+ | Column Name | Type | +-----------------------------+---------+ | delivery_id | int | | customer_id | int | | order_date | date | | customer_pref_delivery_date | date | +-----------------------------+---------+ delivery_id is the column of unique values of this table. The table holds information about food delivery to customers that make orders at some date and specify a preferred delivery date (on the same order date or after it).
Quick Facts
- Difficulty: Medium
- Premium: No
- 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 |
+-----------------------------+---------+
| delivery_id | int |
| customer_id | int |
| order_date | date |
| customer_pref_delivery_date | date |
+-----------------------------+---------+
delivery_id is the column of unique values of this table.
The table holds information about food delivery to customers that make orders at some date and specify a preferred delivery date (on the same order date or after it).
Python Solution
import duckdb
import pandas as pd
def solution(delivery: pd.DataFrame) -> pd.DataFrame:
con = duckdb.connect()
con.register("Delivery", delivery)
return con.execute("""SELECT
ROUND(AVG(order_date = customer_pref_delivery_date) * 100, 2) AS immediate_percentage
FROM Delivery
WHERE
(customer_id, order_date) IN (
SELECT customer_id, MIN(order_date)
FROM Delivery
GROUP BY 1
);""").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.