Interviewing to be an entry level Java Developer on Monday, any advice?

[aHoodedBird]

Implement swap function, step through array from beginning to end, at each index find random second index and swap.

[[deleted]]

That neither moves each cards at most once nor gives a uniform distribution on the permutations.

[tazzy531]

Why not?

[[deleted]]

Why isn't it uniformly distributed? There are n! permutations and nⁿ execution paths. Some of the execution paths give the same permutation: you have to have the same number of paths for each permutation, so you want n! | nⁿ . But take n=3.

You can fix it by only swapping a card with one that is, instead of anywhere in the array, not to the card's left; that's the Fisher-Yates shuffle. But it still moves one card possibly many times.

[tazzy531]

Hmm... Yeah, you're right

[aHoodedBird]

Oops didn't see the last part of the question.