I was referred by a friend. After three weeks, I received a phone call to set up an interview.

I must say that the interviewer wasn't very pleasant. He decided to cut the interview short after he saw I was having a difficult time solving the questions.

Create a random string (without using library functions) with a given length.

Sort an array by mod 3: All elements of mod 3 = 0 would be before all elements of mod 3 = 1, and so on. Do it in linear time.

Given an unsorted array and an integer k, find all pairs of numbers from the array that sum up to k.

Print the power set of the given set.

Explain how a hash table works.