Tournament algorithm in php

Question

I need some help. I want to create one tournament. Let's say I have 6 players. 1 2 3 4 5 6

I want to create some.. lets' say stages... Every player will play 5 matches(number of players - 1), in 5 different stages. In one stage, all the players must appear only once.

For example, with 6 players I want to generate these results:

Squad 1:

1-2
3-4
5-6

Squad 2:

1-3
2-5
4-6

Squad 3:

1-4
2-6
3-5

Squad 4:

1-5
2-4
3-6

Squad 5:

1-6
2-3
4-5

So, in every stage, the matches must be unique, and every player must play with every player.

I want one algorithm that will work even if I want 8 players, or 12, or 16, or 28.

Thanks

Answer 1

<?php
$numplayers = 6;
if ($numplayers % 2 != 0) $numplayers++; // Dummy

for ($round = 0;$round < $numplayers - 1;$round++) {
    echo 'Squad ' . ($round+1) . ":\n\n1-";

    for ($i = 0;$i < $numplayers-1;$i++) {
        if ($i % 2 == 0) {
            $player = ($numplayers-2) - ($i/2) - $round;
        } else {
            $player = ((($i-1)/2) - $round);
        }
        if ($player < 0) $player += $numplayers - 1;
        echo ($player+2);
        echo ($i % 2 == 0) ? "\n" : '-';
    }
    echo "\n\n";
}