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Design a Course Registration System - Low-Level Design | OneNoughtOne

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Design a Course Registration System

Intermediate

Design an object-oriented course registration system for a university that supports a course catalogue with prerequisites, per-semester course offerings (sections) with time slots and capacity limits, multi-step enrollment validation, waitlist management, and academic grading.

Enrollment validates five conditions: (1) student is active, (2) prerequisites are completed, (3) credit limit is not exceeded, (4) no schedule conflict with current courses, and (5) the course is not full (otherwise waitlisted). Dropping a course auto-promotes the first waitlisted student. Time slots use day + start/end times with overlap detection for conflict checking.

Core Use Cases

Manage course catalogue

Add courses with code, name, credits, department, and prerequisites

Create course offerings

Create sections with instructor, room, time slots, capacity for a semester

Enroll student

Enroll after validating prerequisites, credit limit, schedule conflicts, and capacity

Drop course

Drop a student from an offering and auto-promote from waitlist

Waitlist management

Automatically waitlist when course is full; promote when a seat opens

Schedule conflict detection

Prevent enrollment if time slots overlap with any currently enrolled course

Prerequisite validation

Verify all prerequisite courses are completed before enrollment

Credit limit enforcement

Ensure total credits don't exceed the student's per-semester max

Grading and transcript

Assign grades at semester end; generate academic transcript

Constraints

Enrollment only allowed when offering status is OPEN
Student cannot enroll in two sections of the same course
Time slot conflict detection: two slots overlap if same day and time ranges intersect
Prerequisites are transitive: if C requires B and B requires A, student must have A and B
Credit limit is configurable per student (default 24)
Waitlist is FIFO: first waitlisted student gets the first available seat

Assumptions

In-memory storage (no database)
Single university / institution
Sequential enrollment (no concurrent requests)
Grades are letter grades (A, B+, B, C+, C, D, F)
Semesters are string identifiers (e.g. 'Fall2025')

In Scope

Course catalogue with prerequisites
Course offerings (sections) with time slots and capacity
Student enrollment with 5-way validation
Waitlist with auto-promotion on drop
Schedule conflict detection via time slot overlap
Credit limit enforcement
Grade assignment and transcript
Search / query courses by department, semester, keyword

Out of Scope

Payment / tuition fee management
Classroom allocation optimisation
Online / async course handling
Academic probation / GPA rules
Instructor preference / workload balancing
Student advisor approval workflows

Approach Guide(Click to expand each section)

Before diving into code, clarify the use cases and edge cases. Understanding the problem deeply leads to better class design.

List Core Use Cases

Identify the primary actions users will perform. For a parking lot: park vehicle, exit vehicle, check availability. Each becomes a method.

Identify Actors

Who interacts with the system? Customers, admins, automated systems? Each actor type may need different interfaces.

Clarify Constraints

What are the limits? Max vehicles, supported vehicle types, payment methods. Constraints drive your data structures.

Ask About Edge Cases

What happens on overflow? Concurrent access? Payment failures? Thinking about edge cases reveals hidden complexity.

Follow-up Questions(Questions an interviewer might ask)

💡 Draw UML class diagrams, sequence diagrams, or any design visualizations. Submit from the Code tab.

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00:00:00

Design a Course Registration System

Intermediate

Core Use Cases

Manage course catalogue

Add courses with code, name, credits, department, and prerequisites

Create course offerings

Create sections with instructor, room, time slots, capacity for a semester

Enroll student

Enroll after validating prerequisites, credit limit, schedule conflicts, and capacity

Drop course

Drop a student from an offering and auto-promote from waitlist

Waitlist management

Automatically waitlist when course is full; promote when a seat opens

Schedule conflict detection

Prevent enrollment if time slots overlap with any currently enrolled course

Prerequisite validation

Verify all prerequisite courses are completed before enrollment

Credit limit enforcement

Ensure total credits don't exceed the student's per-semester max

Grading and transcript

Assign grades at semester end; generate academic transcript

Constraints

Enrollment only allowed when offering status is OPEN
Student cannot enroll in two sections of the same course
Time slot conflict detection: two slots overlap if same day and time ranges intersect
Prerequisites are transitive: if C requires B and B requires A, student must have A and B
Credit limit is configurable per student (default 24)
Waitlist is FIFO: first waitlisted student gets the first available seat

Assumptions

In-memory storage (no database)
Single university / institution
Sequential enrollment (no concurrent requests)
Grades are letter grades (A, B+, B, C+, C, D, F)
Semesters are string identifiers (e.g. 'Fall2025')

In Scope

Course catalogue with prerequisites
Course offerings (sections) with time slots and capacity
Student enrollment with 5-way validation
Waitlist with auto-promotion on drop
Schedule conflict detection via time slot overlap
Credit limit enforcement
Grade assignment and transcript
Search / query courses by department, semester, keyword

Out of Scope

Payment / tuition fee management
Classroom allocation optimisation
Online / async course handling
Academic probation / GPA rules
Instructor preference / workload balancing
Student advisor approval workflows

Approach Guide(Click to expand each section)

Before diving into code, clarify the use cases and edge cases. Understanding the problem deeply leads to better class design.

List Core Use Cases

Identify the primary actions users will perform. For a parking lot: park vehicle, exit vehicle, check availability. Each becomes a method.

Identify Actors

Who interacts with the system? Customers, admins, automated systems? Each actor type may need different interfaces.

Clarify Constraints

What are the limits? Max vehicles, supported vehicle types, payment methods. Constraints drive your data structures.

Ask About Edge Cases

What happens on overflow? Concurrent access? Payment failures? Thinking about edge cases reveals hidden complexity.

Follow-up Questions(Questions an interviewer might ask)

💡 Draw UML class diagrams, sequence diagrams, or any design visualizations. Submit from the Code tab.

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Design a Course Registration System

Core Use Cases

Constraints

Assumptions

In Scope

Out of Scope

Approach Guide(Click to expand each section)

Follow-up Questions(Questions an interviewer might ask)

Explore the full editorial.

Sign in to view submissions

Design a Course Registration System

Core Use Cases

Constraints

Assumptions

In Scope

Out of Scope

Approach Guide(Click to expand each section)

Follow-up Questions(Questions an interviewer might ask)

Explore the full editorial.

Sign in to view submissions

Design a Course Registration System

Core Use Cases

Constraints

Assumptions

In Scope

Out of Scope

Approach Guide(Click to expand each section)

Gather Requirements~3 min

Identify Classes & Entities~4 min

Define Relationships~3 min

Apply Design Patterns~4 min

Apply SOLID Principles~3 min

Code Organization~2 min

Follow-up Questions(Questions an interviewer might ask)

1How would you handle concurrent enrollment requests for the last seat?

2How would you add a priority-based waitlist (e.g. seniors first)?

3How would you implement registration windows (e.g. seniors register first)?

4How would you add course co-requisites (must take simultaneously)?

5How would you compute GPA and academic standing?

Key Topics

Asked At

Explore the full editorial.

Sign in to view submissions

Design a Course Registration System

Core Use Cases

Constraints

Assumptions

In Scope

Out of Scope

Approach Guide(Click to expand each section)

Gather Requirements~3 min

Identify Classes & Entities~4 min

Define Relationships~3 min

Apply Design Patterns~4 min

Apply SOLID Principles~3 min

Code Organization~2 min

Follow-up Questions(Questions an interviewer might ask)

1How would you handle concurrent enrollment requests for the last seat?

2How would you add a priority-based waitlist (e.g. seniors first)?

3How would you implement registration windows (e.g. seniors register first)?

4How would you add course co-requisites (must take simultaneously)?

5How would you compute GPA and academic standing?

Key Topics

Asked At

Explore the full editorial.

Sign in to view submissions