Math problem

[LGM]

Originally posted by geoschmo:

quote:

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Originally posted by LGM:
I used a program. Here are two solutions:

N=7
3,5,6
3,4,7
2,5,7
2,4,6
1,6,7
1,4,5
1,2,3

This isn't what I was looking for. This is everybody playing 3 three man games. I wanted everybody to play EVERYBODY else once and only once in a three man game. 7 players won't work for that. You need a power of 3 as Spoon says so 9, or 27, etc.

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I am not sure I follow. Player 1 places all 3 player games and plays every player once and only once. The same applies for player 2, 3, etc.

[spoon]

Originally posted by geoschmo:
How did you calculate nine games each for 27 players in a 3 on 3 tourney though? With 27 player field if you play everybody once and only once and do it with 3 man games that would be (27-1)/2=13 games. With a nine player player field it would be (9-1)/2=4 games each.

Geoschmo

Oh that? Must be programmer error... heh. That's why you should never listen to them...

[LGM]

Originally posted by geoschmo:
Assume a hypothetical tournament which are all 3 player games. In the tournament everybody has to play everybody else once, but only once.

What part of the requirement did I neglect?

[geoschmo]

Oh wait LGM, I think I see what you are saying now. Did your program find solutions for anything between 7 and 15. The way I am looking at this now it should be possible to do for many numbers, not just powers of x.

Approaching the problem from the other end was the key if I am correct. For example, in a tournament of three man games the minimum number of players would be 3, and the number of games would be 1. The forumula should be:

x, game size
y, number of tourney games
n, total tourney field

EDIT: IGNORE EVERYTHING IN THIS POST AFTER THIS POINT. I haven't figured out what I did wrong, but this isn't right at all.

(y(x-1))+1=n

plugging in the ones we know already
(1(3-1))+1=3
(3(3-1))+1=7
(7(3-1))+1=15
(13(3-1))+1=27

We should be able to work out an n for any positive real integer X and Y fairly easy.
If x=3
y=1, n=3
y=2, n=5
y=3, n=7
y=4, n=9
.
.
y=15, n=31

So for x=3 n can be any odd number except 1.

The hard part would be actually coming up with the y number of combinations so that each player doesn't play anyone else more then once.

[ August 06, 2003, 20:44: Message edited by: geoschmo ]

[geoschmo]

No, that's not right.

LGM, I didn't mean any offense. I looked at your initial post and didn't think it solved teh problme, but after looking at it again I see it does. Can you explain the math your program is doing to find the solutions? That is what I am trying to figure out.

Geoschmo

[Slick]

I didn't read all the replies, so pardon this if already stated, but aren't you talking about the statistical formula for combinations? Mathematically, it means: how many ways can I group n things in groupings of r where the order of grouping is not important. (There is a separate formula for permutations where order is important)

The general formula for C(n,r) = n!/[r!(n-r)!]

Where the number of combinations C(n,r) is a function of the total number of people n taken r at a time.

You don't need any particular number of players to start with. If n = 10 and r = 3 then the required number of games is 10!/[3!x7!] = 120

Exactly how to arrange the people in each game is most easily worked out by hand although I suppose it could be done with a program.

Slick.

[LGM]

Only solutions are 3, 7, 15, 31,...

Other numbers of players leave a three some with two players and no one to match them with. Someone demonstrated this earlier with 9 players.