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

Posted by Cocorico on Stack Overflow See other posts from Stack Overflow or by Cocorico
Published on 2010-03-23T18:02:06Z Indexed on 2010/03/23 21:23 UTC
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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 also between 0 and 49 (I am using Objective C but this is more of a general theory question I think?).

Method I thought of is:

 int a;
 int b;
 int c;

 do {
  a = arc4random() % 49;
 } while ((a == x) || (a == y));

 do {
  b = arc4random() % 49;
 } while ((b == x) || (b == y) || (b == a));

 do {
  c = arc4random() % 49;
 } while ((c == x) || (c == y) || (c == a) || (c == b));

But it seem kind of bad to me, I don't know, I am just trying to learn to be a better programmer, what would be the most elegant way to do this for best practices?

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