Honestly I am not sure if you are looking for the right way to prepare for case interviews.
Having good solutions help a bit to get a broad idea how cases develop over time. However, a case interview is an interactive situation and you need to adapt along new pieces of information along the way, based on your questions and the information you receive from the interviewer.
Knowing the solution doesn't really help that much for prep - actually it makes candidates more thinking like a robot in if-then scenarios, rather than starting to develop their thinking like a consultant and having good discussions with the interviewer.
So be careful to not confuse interview prep with following solutions from written cases.. not what will get you an offer.
Hope that helps - if so, please be so kind and give it a thumbs-up with the green upvote button below!