This is simple yet very important subject. Knowledge of time complexity is a must for any kind of system you will build later as well as the data structures you will be using there.

From exam point of view this is a fairly easy subject. a lot of programming so if you struggle with programming this is even good for you because instead of making you write code this subject forces you to think why the code works.

All chapters are important and i wouldn't recommend skipping any but if you are short on time you may just watch important videos from tree and graph and skip this cahpter.

This subject has the best videos you could learn from because of the importance of this subject there are many good videos on youtube. so this may be the best subject to learn from youtube.