A staple in Capgemini interview questions technical, be prepared to answer this one. A rapid sort typically works best in ordinary instances, although there are certain exceptions. In most cases, it is O(N log N), but in the worst situation, it is O(N2). You should utilize rapid sort in cases where average-case performance is more important than focusing on the worst-case scenario. To respond, you'll need to have a thorough grasp of algorithms and their performance/implementation.  An array does not have a fixed structure for adding or retrieving data, whereas a stack uses a strict LIFO approach (last in and first out). Questions like this will put your knowledge of data structures and your ability to memorise to the test.