I applied for an internship at my university during my second year of study.

The recruitment process had two rounds.

First was a coding round, which had two questions and one hour to solve.

Second was an interview with one of the engineers at Microsoft.

Both rounds were easy if you knew basic data structures like heaps, trees, and arrays.

Coding Round:

One standard question on min-heap had to do something with heapsort. One question where, given a board game on a grid, you need to find your path with simple moves as given in the rules and find some quantity like total path length.

Interview:

Basic CV questions, mention one project and what you did in that.

Technical questions: Given an array of length n with elements from 0 to n and one element missing in an unsorted manner, tell the missing element.

Further questions built up on this, like improving the time complexity and space complexity.

What is the time complexity?