Can someone suggest a good algorithm for the following problem (or a reference to look up)?
You have a set of numbers from 1 to $m$ (m=80) (inclusive). $n$ (=20) non-repeating numbers will be drawn from the set in an increasing order in a single draw. There will be 2 to N draws, and you will have the results of those draws. Design an algorithm, which will find the most and the least repeated group ($N$-members) of numbers in the draws.
Sample draws
1) 4 5 7 19 28 32 39 40 43 44 46 47 48 49 55 56 59 69 73 79 2) 1 10 11 19 20 27 32 35 41 42 46 49 51 54 58 61 63 67 68 76 3) 3 4 5 8 11 16 24 25 27 34 37 48 49 50 57 58 59 68 71 73 4) 1 8 10 13 18 26 27 30 32 35 45 46 49 52 53 61 66 72 75 78 5) 7 14 20 21 25 26 38 40 43 46 49 53 54 58 60 61 66 68 74 80
Further explanation
The algorithm should find the most repeating group of N-numbers (say 3 numbers). So, basically a tuple of three numbers that is repeated the most in the draws must be found. it is also possible that there will be a most/least common group of $N$-members, but it is quite as possible that there won't.