Interviewers were friendly, had 3 rounds of coding, a behavioral and a system design round

Round 1 :
Kth Largest element
Next Permutation

Round 2
Serialize and Deserialize a binary tree

Round 3
Valid Paliandrome II
Consecuttive Sequence with given sum

System Design
Online Coding Competition Platform

Behavioural Round
Normal friendly questions.

How I prepared?

I started by refreshing my knowledge in data structures, best place to start would be from trees, Linked lists, Arrays Hashsets etc
Then got a good grip on BFS,DFS,Treetraversals,Topological sort etc. Prepared on questions based on frequencies, was able to go through around 75 questions