Question

I was asked this question in an interview and I gave various solutions but the interviewer was not convinced. I am interested to find a solution. Please throw in your views :

Q: Write an efficient data structure to implement the shuffle in an ipod. It must play all the songs, each time in different random order, the same song should not be repeated. ( mostly O(n))

One solution , I thought off after the interview : I can do a randomized quick sort without recursion. Where we randomly, chose 1 pivot O(1) and then do quicksort O(n). Now songs will be sorted in some order and I play them till the end. Once it reaches the end, I will Again chose a random pivot and , repeat this process again and again.

Regards,
Sethu

Answer 1

Place all the songs in an array…
For each element in the array swap it with a random position.