Checked the profile: School 21 explains a lot. I hope this is your solution and not a copy-paste job. Funny, that you removed ft_ from the function names.

Good to see a nicely formatted and easy-to-read code. Does not happen too often.

yes ofcourse it becomes less readable, but using numbers makes ur basics stronger as you practice.

Really nice solution. I did it in a similiar way, but your code is a lot smarter and shorter.

Using numbers instead of characters, e.g. 97 instead of 'a' makes any code significantly less readable.

For only one type of brackets using stack is kind of an overkill.