What a fortunate thing, that we're in a coding site, not an interview.

If I didn't want to use libraries then I would've coded in C lol.

Sorry to say, that's not accepted in a real interview. Your interviewer has given you the question to check whether you can whether you can solve it without using libraries. They expect you to understand how things work under the hood.

Good job! I don't know why someone should reinvent the wheel, when there is a tested library, that does exactly that.