Every company that comes to campus makes you sit an OA before anyone talks to you. That is where most people get cut, and not because they are weak at coding. It is a timed test on a fixed set of things: arrays, hashing, two pointers, recursion, trees, graphs, DP. If you have solved enough of those, the questions look familiar. If you have not, no amount of thinking on the spot will save you. So do them now, while there is time. This roadmap is that set, week by week.