NiCE Student Software Engineer interview questions

The first question was to tell about a project you had done, the second was to explain how to sort 4 numbers with a "machine" built out of small "machines" that sort 2 numbers, the third was to pick a design for a program of a stop-watch, the last question was about a code of two threads and what result it prints out.

The best algorithm to find two numbers in array which their difference is delta.