The three bare minimum books that one must study before reaching campus?


I came across the list of books on the thread. However, to be frank, it is not possible to read them in a period of 3-4 months along with a full time job (or full time academic activity). For a person fairly conversant with basic c++, python, finance and statistics and interested in having a good shot at Quantitative Research roles, what are the three core books one must read before reaching campus?
I would say solving leetcode maybe a better use of time. As for textbook, read about linear algebra first if you have to pick one.