Need help with logic, make three dimensional array (PHP) - php

Question

I need help, example, i got array with 4 for team names there.
array('logiX.L4d22','Lust','Marat and Friends','Pandas of Belgium');
I want to make 3 dimensional array where first is a round, second is a match, and the third is teams who plays with eachother, there will be always 2 teams.
the logic must make that all teams must be played with all others and in one round, any team will play only one match, so if we got 5 teams then in some round one team must just wait to the next round.
it must produce something like this:
array
0 =>
array
0 =>
array
0 => string 'logiX.L4D2' (length=10)
1 => string 'Lust' (length=4)
1 =>
array
0 => string 'Marat and Friends' (length=17)
1 => string 'Pandas of Belgium' (length=17)
1 =>
array
0 =>
array
0 => string 'logiX.L4D2' (length=10)
1 => string 'Marat and Friends' (length=17)
1 =>
array
0 => string 'Lust' (length=4)
1 => string 'Pandas of Belgium' (length=17)
2 =>
array
0 =>
array
0 => string 'logiX.L4D2' (length=10)
1 => string 'Pandas of Belgium' (length=17)
1 =>
array
0 => string 'Lust' (length=4)
1 => string 'Marat and Friends' (length=17)
It must be work with 2,3,5 ...10 ...12 teams.
I hope that you can help me out, i already spent 1 and half days for that.

Answer 1

Some Googling on Round Robin algorithm PHP gives the following:
http://speedtech.it/blog/2009/03/15/round-robin-algorithm-php/
http://www.phpbuilder.com/board/showthread.php?t=10300945
I hope you'll find what you're looking for.
EDIT
Adding my attempt for this, following the round-robin algorithm described on Wikipedia.
If teams number is odd, it adds a team in the array (null value), so you can retrieve the "waiting team" for each round.
<?php
$teams = range('a', 'g');
function make_rounds($teams)
{
$nb_teams = count($teams);
if ($nb_teams % 2 != 0)
{
$teams[] = null;
$nb_teams++;
}
$nb_rounds = $nb_teams - 1;
$nb_matches = $nb_teams / 2;
$rounds = array();
for($round_index = 0; $round_index < $nb_rounds; $round_index++)
{
$matches = array();
for($match_index = 0; $match_index < $nb_matches; $match_index++)
{
if ($match_index == 0)
$first_team = $teams[0];
else
$first_team = $teams[(($nb_teams-2) + $match_index - $round_index) % ($nb_teams-1) + 1];
$second_team = $teams[(($nb_teams*2) - $match_index - $round_index - 3) % ($nb_teams-1) + 1];
$matches[] = array($first_team, $second_team);
}
$rounds[] = $matches;
}
return $rounds;
}
print_r(make_rounds($teams));

Answer 2

My version of solution. I would call it brute force. However, it works somehow. (Or it looks like that.)
<?php
$a = array('a','b','c','d','e','f','g');
function do_array($a)
{
$lim = sizeof($a) - 1;
# Create an array of all matches to play.
$cross = array(array());
foreach (range(0,$lim) as $k_row):
foreach (range(0,$lim) as $k_col):
if ($k_row >= $k_col):
$toput = false;
else:
$toput = array($a[$k_row],$a[$k_col]);
endif;
$cross[$k_row][$k_col] = $toput;
endforeach;
endforeach;
$ret = array();
foreach (range(0,$lim) as $k_round):
$round = array();
# $tmp array holds all possible matches
# to play in current round.
$tmp = $cross;
$i = 0;
foreach (range(0,$lim) as $k_row):
foreach (range(0,$lim) as $k_col):
if ($math = $tmp[$k_row][$k_col]):
$cross[$k_row][$k_col] = false;
# These matches are not possible
# in the current round.
foreach (range(0,$lim) as $k):
$tmp[$k][$k_col] = false;
$tmp[$k][$k_row] = false;
$tmp[$k_col][$k] = false;
$tmp[$k_row][$k] = false;
endforeach;
$round[] = $math;
endif;
endforeach;
endforeach;
if ($round):
$ret[] = $round;
endif;
endforeach;
return $ret;
}
print_r (do_array($a));
?>