Design a Library Management System | Machine Coding Round Questions (SDE II)

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Problem Statement

A library management system is an automation system used to manage a library and the different resource management required in it like cataloging of books, allowing check out and return of books, invoicing, user management, etc.

For this problem, we have to design a library management system that can do a few of the above functionalities.

Requirements

Create a command-line application for the library management system with the following requirements.

Details about the Library:

The library will have one or more copies of multiple books
The library will have multiple racks and each rack can contain at most one copy of any book.

Each book will have the following properties:

Book ID
Title
Authors
Publishers

Details about Book Copies

There could be multiple copies of the same book.
Each book copy will have a unique ID.
Each book copy will be placed on a rack.
Each book copy can be borrowed by a user with a specific due date.

Every rack will have a unique rack number (numbered serially from 1 to n where n is the total number of racks).
Details about User:

User details: User ID, Name
A user can borrow a maximum of 5 books.

The functions that the library management system can do:

Create a library.
Add a book to the library. The book should be added to the first available rack.
Remove a book copy from the library.
Allow a user to borrow a book copy given the book id, user id, and due date. The first available copy based on the rack number should be provided.
Allow a user to borrow a book copy given the book copy id, user id, and due date.
Allow a user to return a book copy given the book copy id. The book should be added to the first available rack.
Allow a user to print the book copy ids of all the books borrowed by them.
Allow a user to search for books using few book properties (Book ID, Title, Author, Publisher). Searching should return details about all the book copies that match the search query.

Input/Output Format

The code should strictly follow the input/output format and will be tested with provided test cases.

Input Format

Multiple lines with each line containing a command.

Possible commands:

create_library <library_id> <no_of_racks>
add_book <book_id> <title> <comma_separated_authors> <comma_separated_publishers> <comma_separated_book_copy_ids>
remove_book_copy <book_copy_id>
borrow_book <book_id> <user_id> <due_date>
borrow_book_copy <book_copy_id> <user_id> <due_date>
return_book_copy <book_copy_id>
print_borrowed <user_id>
search <attribute> <attribute_value>

Possible values of attribute: book_id, author, publisher

exit

Stop taking the input when you encounter the word exit.

Note: You can assume that there would be no spaces in the book title or names of publishers/authors.

Output Format

Print output based on the specific commands as mentioned below.

create_library

Created library with <no_of_racks> racks

add_book

Added Book to racks: <comma_separated_rack_nos>

Print "Rack not available" if there are not enough racks available and reject this add request.

remove_book_copy

Removed book copy: <book_copy_id> from rack: <rack_no>

Print "Invalid Book Copy ID" if the book copy is not present in any of the racks.

borrow_book

Borrowed Book from rack: <rack_no>

Print "Invalid Book ID" if book id is invalid.

Print "Not available" if no more copies of that book are available.

Print "Overlimit" if the user has already borrowed 5 books.

borrow_book_copy

Borrowed Book Copy from rack: <rack_no>

Print "Invalid Book Copy ID" if the book copy is not present in any of the racks.

Print "Overlimit" if the user has already borrowed 5 books.

return_book_copy

Returned book copy <book_copy_id> and added to rack: <rack_no>

Print "Invalid Book Copy ID" if the book copy id is not present in the system.

Assume that the book copy is not already present on the rack.

print_borrowed

Book Copy: <book_copy_id> <due_date>

The above will be printed for each borrowed book copy.

Do not print anything if no book is borrowed

Print in ascending order of book_copy_id.

search

Book Copy: <book_copy_id> <book_id> <title> <comma_separated_authors> <comma_separated_publishers> <rack_no> <borrowed_by_id> <due_date>

The above will be printed for each copy (irrespective of whether it is borrowed or not).

If the book is borrowed, rack_no will be -1

If the book is not borrowed, do not print borrowed_by_id and due_date

If the library does not own that book then do not print anything

Print in ascending order of rack number.

Examples

Sample Input

create_library 10
add_book 1 book1 author1,author2 publisher1 book_copy1,book_copy2,book_copy3
add_book 2 book2 author2,author3 publisher2,publisher3 book_copy4,book_copy5,book_copy6,book_copy7,book_copy8,book_copy9,book_copy10
add_book 3 book3 author2 publisher2 book_copy11,book_copy12,book_copy13
search book_id 1
search book_id 3
search author_id author2
search author_id author3
remove_book_copy book_copy6
remove_book_copy book_copy13
add_book 3 book3 author2 publisher2 book_copy13
search book_id 2
print_borrowed user1
borrow_book 1 user1 2020-12-31
borrow_book 1 user1 2020-12-31
borrow_book 1 user1 2020-12-31
borrow_book 1 user1 2020-12-31
search book_id 1
search author_id author1
borrow_book 4 user1 2020-12-31
borrow_book 2 user1 2020-12-31
borrow_book 2 user1 2020-12-31
borrow_book 2 user1 2020-12-31
print_borrowed user1
return_book_copy book_copy1
return_book_copy book_copy2
borrow_book_copy book_copy1
borrow_book_copy book_copy1
borrow_book_copy book_copy2
borrow_book_copy book_copy10
print_borrowed user1
exit

Expected Output

Created library with 10 racks
Added Book to racks: 1,2,3
Added Book to racks: 4,5,6,7,8,9,10
Rack not available
Book Copy: book_copy1 1 book1 author1,author2 publisher1 1
Book Copy: book_copy2 1 book1 author1,author2 publisher1 2
Book Copy: book_copy3 1 book1 author1,author2 publisher1 3
Book Copy: book_copy1 1 book1 author1,author2 publisher1 1
Book Copy: book_copy2 1 book1 author1,author2 publisher1 2
Book Copy: book_copy3 1 book1 author1,author2 publisher1 3
Book Copy: book_copy4 2 book2 author2,author3 publisher2,publisher3 4
Book Copy: book_copy5 2 book2 author2,author3 publisher2,publisher3 5
Book Copy: book_copy6 2 book2 author2,author3 publisher2,publisher3 6
Book Copy: book_copy7 2 book2 author2,author3 publisher2,publisher3 7
Book Copy: book_copy8 2 book2 author2,author3 publisher2,publisher3 8
Book Copy: book_copy9 2 book2 author2,author3 publisher2,publisher3 9
Book Copy: book_copy10 2 book2 author2,author3 publisher2,publisher3 10
Book Copy: book_copy4 2 book2 author2,author3 publisher2,publisher3 4
Book Copy: book_copy5 2 book2 author2,author3 publisher2,publisher3 5
Book Copy: book_copy6 2 book2 author2,author3 publisher2,publisher3 6
Book Copy: book_copy7 2 book2 author2,author3 publisher2,publisher3 7
Book Copy: book_copy8 2 book2 author2,author3 publisher2,publisher3 8
Book Copy: book_copy9 2 book2 author2,author3 publisher2,publisher3 9
Book Copy: book_copy10 2 book2 author2,author3 publisher2,publisher3 10
Removed book copy: book_copy6 from rack: 6
Invalid Book Copy ID
Added Book to racks: 6
Book Copy: book_copy4 2 book2 author2,author3 publisher2,publisher3 4
Book Copy: book_copy5 2 book2 author2,author3 publisher2,publisher3 5
Book Copy: book_copy7 2 book2 author2,author3 publisher2,publisher3 7
Book Copy: book_copy8 2 book2 author2,author3 publisher2,publisher3 8
Book Copy: book_copy9 2 book2 author2,author3 publisher2,publisher3 9
Book Copy: book_copy10 2 book2 author2,author3 publisher2,publisher3 10
Borrowed Book from rack: 1
Borrowed Book from rack: 2
Borrowed Book from rack: 3
Not available
Book Copy: book_copy1 1 book1 author1,author2 publisher1 -1 user1 2020-12-31
Book Copy: book_copy2 1 book1 author1,author2 publisher1 -1 user1 2020-12-31
Book Copy: book_copy3 1 book1 author1,author2 publisher1 -1 user1 2020-12-31
Book Copy: book_copy1 1 book1 author1,author2 publisher1 -1 user1 2020-12-31
Book Copy: book_copy2 1 book1 author1,author2 publisher1 -1 user1 2020-12-31
Book Copy: book_copy3 1 book1 author1,author2 publisher1 -1 user1 2020-12-31
Invalid Book ID
Borrowed Book from rack: 4
Borrowed Book from rack: 5
Overlimit
Book Copy: book_copy1 2020-12-31
Book Copy: book_copy2 2020-12-31
Book Copy: book_copy3 2020-12-31
Book Copy: book_copy4 2020-12-31
Book Copy: book_copy5 2020-12-31
Returned book copy book_copy1 and added to rack: 1
Returned book copy book_copy2 and added to rack: 2
Borrowed Book from rack: 1
Invalid Book Copy ID
Borrowed Book from rack: 2
Overlimit
Book Copy: book_copy1 2020-12-31
Book Copy: book_copy2 2020-12-31
Book Copy: book_copy3 2020-12-31
Book Copy: book_copy4 2020-12-31
Book Copy: book_copy5 2020-12-31

Expectations

Make sure that you have a working and demonstrable code
Make sure that the code is functionally correct
Code should be modular and readable
Separation of concern should be addressed
Please do not write everything in a single file (if not coding in C/C++)
Code should easily accommodate new requirements and minimal changes
There should be a main method from where the code could be easily testable
[Optional] Write unit tests, if possible
No need to create a GUI

Optional Requirements

Please do these only if you’ve time left. You can write your code such that these could be accommodated without changing your code much.

Keep the code extensible to change the number of books users can borrow.
Keep the code extensible to add more attributes to the book and the book search system.
Keep the system thread-safe to allow concurrent requests.