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.InputThe first line contains two integers:  \$n\$ and \$k\$ (\$1n,k1000\$).OutputIn 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\$ (\$1ai\$,\$bin\$; \$aibi\$). 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:<?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 * $k > ($n * ($n - 1)) / 2) {    echo -1\n;exit;}$output = $n*$k.\n;$winMap = array();for ($i = 1; $i <= $n; $i++) {    $winMap[$i] = 0;}for ($i = 1; $i <= $n; $i++) {    for ($j = $i + 1; $j <= $n; $j++) {        if ($winMap[$i] < $k) {            $output .= $i $j\n;            $winMap[$i] += 1;        } else if ($winMap[$j] < $k) {            $winMap[$j] += 1;            $output .=  $j $i\n;        }    }}echo $output;?>
Programming Puzzle - N Teams K Wins each
php;algorithm;programming challenge