While happy with my current job, I was connected to a recruiter through LinkedIn. They forwarded my resume to one of the teams.

I had a phone interview with the Yahoo! Mail Search team. The questions asked were something like finding possible substrings in a string and some C++ concept questions.

The interviewer was the worst I have ever experienced. I was pretty sure she didn't bother going through my resume before the phone interview. She was very rude and not paying attention to my answers. At the end, we ran out of time, and she didn't let me ask questions because she was in a hurry to get off the phone.

Write a program that finds all repeated substrings in a given string and provide the time complexity of this program. How can you make it perform better in terms of time and memory?