Leetcode #1988: Find Cutoff Score for Each School
In this guide, we solve Leetcode #1988 Find Cutoff Score for Each School 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: Schools +-------------+------+ | Column Name | Type | +-------------+------+ | school_id | int | | capacity | int | +-------------+------+ school_id is the column with unique values for this table. This table contains information about the capacity of some schools.
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 |
+-------------+------+
| school_id | int |
| capacity | int |
+-------------+------+
school_id is the column with unique values for this table.
This table contains information about the capacity of some schools. The capacity is the maximum number of students the school can accept.
Python Solution
import duckdb
import pandas as pd
def solution(schools: pd.DataFrame, exam: pd.DataFrame) -> pd.DataFrame:
con = duckdb.connect()
con.register("Schools", schools)
con.register("Exam", exam)
return con.execute("""SELECT school_id, MIN(IFNULL(score, -1)) AS score
FROM
Schools AS s
LEFT JOIN Exam AS e ON s.capacity >= e.student_count
GROUP BY school_id;""").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.