Algorithm for creating unique bingo faces

Question

Hi,

Does anyone know of an algorithm that can generate unique bingo card faces? I'm looking to implement this algorithm in C#.

Thanks,

Answer 1

get 5 sets containing 15 numbers each (1-15 for set 1, 16-30 for set 2...)
select 5 different numbers in sets 1,2,4,5
select 4 different numbers in set 3

To check if that card already exists
Check each existing card for top left correspondance with new card
if both numbers are equal, then move to the second number
if you get 24 times the same number at the same place then both cards are equal and new card must be rejected

Answer 2

This is an interesting problem, but as Michael Madsen reported, given the number of possibilities, you would probably be better generate them randomly and after, check if you have duplicates. (Unless you want to generate all 111 quadrillion possibilities, which I hope you have data storage space for!)

Answer 3

Here's a function for generating a random subset of integers from a given range which you might find useful:

private static IEnumerable<int> RandomSubsetOfRange(int min, int max, int count)
{
    Random random = new Random();

    int size = max - min + 1;
    for (int i = 0; i <= size; i += 1)
    {
        if (random.NextDouble() <= ((float)count / (float)(size - i + 1)))
        {
            yield return min + i;
            count -= 1;
        }
    }
}