I thought every problem will be hard dp and prepared dp for 2 months and got spectacularly messed up.
First problem
Easy probelm was from sliding window I didnt solve a single sliding window recently still managed to pass 6 cases.
Question: A binary String need to return the maximum length of subarray where the no of zeros and ones should be same and you can do k flips.
Second problem
It is purely an optimisation technique based ig i tired to solve it but it requires optimisation no tree, no graph , no dp.(question is bit complex but there was no idea for me to solve it so i am guessing it based on optimisation on brute force)
Third problem
It was tagged hard and had the suprise, it was a LinkedList problem some bit operations required create some proper next nodes then a simple LinkedList and it had cycle detections as well you need stop adding the values to the answer once you enter into a cycle.
Complex problem At last it was a hard graph + dp ig cant able to figure anything else. But the state change at every level felt like the dp Dugeon game problem in a graph with some updates as you enter each node.

An complete failure!! Quite disappointed as i was grinding dp and dp on tree in an advanced version for last two months for it but all topics were different.(Got fed up from online sources saying only dp was asked).
No chance for DSE even!!!
Hope this helps someone and will comeback here in future.