It was an on-campus hiring process. After two rounds of online assessments, there were three rounds of interviews, each lasting about 45 minutes.

• Round 1: I was questioned at length on the projects in my resume, followed by some data structure questions (Binary Trees), and ending with a puzzle.
• Round 2: There were many questions on OOPS, then some coding questions of easy difficulty. We also discussed sorting algorithms, their complexities, and slight variations of common algorithms.
• Round 3: This round was more laid back, involving a casual discussion of my interests, my knowledge in different programming languages, and advice on what I should focus on in the future.

Given the root of a binary tree, make it its mirror image.

Construct a balanced Binary Search Tree from an unsorted random input.

Given an array of integers and a key element, put all key element occurrences at the end of the array. Use O(1) space and O(n) time complexity.