How can I efficiently select several unique random numbers from 1 to 50, excluding x?

Question

I have 2 numbers which are between 0 and 49. Let\'s call them x and y. Now I want to get a couple of other numbers which are not x or y, but are al

Answer 1

I'd do something more along the lines of:

NSMutableSet * invalidNumbers = [NSMutableSet set];
[invalidNumbers addObject:[NSNumber numberWithInt:x]];
[invalidNumbers addObject:[NSNumber numberWithInt:y]];

int nextRandom = -1;
do {
  if (nextRandom >= 0) {
    [invalidNumbers addObject:[NSNumber numberWithInt:nextRandome]];
  }
  nextRandom = arc4random() % 49;
} while ([invalidNumbers containsObject:[NSNumber numberWithInt:nextRandom]]);