Algorithm to generate an evenly distributed random permutation [closed] - algorithm

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I have a set of N questions, each one categorized as one of R subjects. I'm trying to generate some random permutation of the questions for a quiz.
How would I generate a random permutation of the set of questions such that no two consecutive questions have the same subject? It does not need to be perfect; I just don't want to bore people with five of the same type of question in a row.
Additionally, if such an ordering is not possible (as in, 18 of A and 2 of B), could the algorithm find an "evenly distributed" permutation? (in this case, something reasonably like 6As, B, 7As, B, 5As)
Alternatively, since I'm delivering the questions sequentially, could I each time randomly select a remaining question of a different subject without the chance of forcing some repeats at the end?
I've looked around randomly on Google for a while and can't seem to find anything that fits this case. Other than randomly generating permutations until you find one that works, which is slow, ugly and stupid.

Answer 1

Here's an idea:
Group your questions into R groups according to their subject.
Shuffle each group separately
Interleave the groups depending on their relative size, so that they are evenly spaced.
This is simple and fits your requirements. A bit of 'randomness' is lost because the interleaving is always the same (i.e. question from subject 1, then from subject 2, then from subject 3, and start with subject 1 again).
This could be improved by randomizing the order in which you pick groups for each iteration.

Answer 2

Remove the previously used subject from the list of candidate subjects.
For example, in Java, suppose you have 10 subjects:
Subject previous = listSubjects.get( 0 );
while( true ){
listCandidateSubjects.remove( previous );
int xSelection = Random.nextInt( 10 );
Subject current = listCandidateSubjects.get( xSelection );
listCandidateSubjects.add( previous );
// generate question for current subject here
// when have enough questions break
previous = current;
}