Programming Puzzle - N Teams K Wins each I found a problem here. I am sharing the problem and my attempt at solution. I would like to find out if this is the best approach possible.


  One day, at the "Russian Code Cup" event it was decided to play
  football as an out of competition event. All participants was divided
  into n teams and played several matches, two teams could not play
  against each other more than once.
  
  The appointed Judge was the most experienced member - Pavel. But since
  he was the wisest of all, he soon got bored of the game and fell
  asleep. Waking up, he discovered that the tournament is over and the
  teams want to know the results of all the matches.
  
  Pavel didn't want anyone to discover about him sleeping and not
  keeping an eye on the results, so he decided to recover the results of
  all games. To do this, he asked all the teams and learned that the
  real winner was friendship, that is, each team beat the other teams
  exactly k times. Help Pavel come up with chronology of the tournir
  that meets all the conditions, or otherwise report that there is no
  such table.
  
  Input
  
  The first line contains two integers:  \$n\$ and \$k\$ (\$1 ≤ n, k ≤ 1000\$).
  
  Output
  
  In the first line print an integer \$m\$ - number of the played
  games. The following \$m\$ lines should contain the information about all
  the matches, one match per line. The \$i\$-th line should contain two
  integers \$ai\$ and \$bi\$ (\$1 ≤ ai\$, \$bi ≤ n\$; \$ai ≠ bi\$). The numbers \$ai\$ and \$bi\$
  mean, that in the \$i\$-th match the team with number \$ai\$ won against the
  team with number \$bi\$. You can assume, that the teams are numbered from
  1 to \$n\$.
  
  If a tournir that meets the conditions of the problem does not exist, then print -1.


My solution:

&lt;?php
//$n = $argv[1];
//$k = $argv[2];
$s = fopen("php://stdin", 'r');
$n = stream_get_contents($s);
$dum= explode(" ",trim($n));
$n=$dum[0];
$k=$dum[1];
if ($n * $k &gt; ($n * ($n - 1)) / 2) {
    echo "-1\n";exit;
}
$output = $n*$k."\n";
$winMap = array();
for ($i = 1; $i &lt;= $n; $i++) {
    $winMap[$i] = 0;
}
for ($i = 1; $i &lt;= $n; $i++) {
    for ($j = $i + 1; $j &lt;= $n; $j++) {
        if ($winMap[$i] &lt; $k) {
            $output .= "$i $j\n";
            $winMap[$i] += 1;
        } else if ($winMap[$j] &lt; $k) {
            $winMap[$j] += 1;
            $output .=  "$j $i\n";
        }
    }
}
echo $output;
?&gt;
Style

You are lacking consistency in the spacing in assignments.

Organisation

It might be worth extracting the algorithm in a function. It makes code easier to read and to test.

&lt;?php
function guessChronology($n, $k)
{
    if ($n * $k &gt; ($n * ($n - 1)) / 2) {
        return "-1\n";
    }
    $output = $n*$k."\n";
    $winMap = array();
    for ($i = 1; $i &lt;= $n; $i++) {
        $winMap[$i] = 0;
    }
    for ($i = 1; $i &lt;= $n; $i++) {
        for ($j = $i + 1; $j &lt;= $n; $j++) {
            if ($winMap[$i] &lt; $k) {
                $output .= "$i $j\n";
                $winMap[$i] += 1;
            } else if ($winMap[$j] &lt; $k) {
                $winMap[$j] += 1;
                $output .=  "$j $i\n";
            }
        }
    }
    return $output;
}

$s = fopen("php://stdin", 'r');
$n = stream_get_contents($s);
$dum = explode(" ",trim($n));
$n = $dum[0];
$k = $dum[1];
echo guessChronology($n, $k);
?&gt;


Re-using functions

You can use array_fill to write $winMap = array_fill(1, $n, 0);