I had a one-hour phone interview with a Senior Engineer.

She asked me to speak about one of my projects and then moved on to a coding challenge.

I walked her through how I would solve the question using O(n) time and O(n) space, but she wanted me to optimize it, requiring me to use O(1) space.

I tried to come up with an O(n log n) solution but failed some of the test cases.

Given her requirements, I was hoping she might provide some hints because she clearly had a specific solution in mind.

We ran out of time, and I didn't get a chance to solve it using the solution I originally proposed.

I received a response after 10 days after emailing the recruiter.

Find missing integers in an array of size n.