php FOR 循环优化有关问题

php FOR 循环优化问题
上次发个帖子没人跟,可能是问题不具体或者php基础编程人少或者太忙.............

我想从1-33选出6个不重复的号,然后写入数据库
现在选号过程PHP处理的很慢还总出错误,谁有兴趣帮我把下面的代码优化下:

PHP code

<?php$str=array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33);for($i=0;$i<28;$i++){    for($j=$i+1;$j<33;$j++){        for($k=$j+1;$k<33;$k++){            for($l=$j+1;$l<33;$l++){                for($m=$l+1;$m<33;$m++){                    for($n=$m+1;$n<33;$n++){                        echo "$str[i]|$str[j]|$str[k]|$str[l]|$str[m]|$str[n]|<br>";//显示效果,本想写入TXT文档在传如数据库.                    }                }            }        }    }}?>

PHP code

$a  = range(1, 33);$ar = combination($a, 6);//求组合高效率的10移动法function combination($numArr,$combineLen) {  $numCt    = count($numArr);  if($combineLen > $numCt) return;  $bin    = str_pad('',$combineLen,'1');  $bin    = str_pad($bin,$numCt,'0',STR_PAD_RIGHT);      $find    = $bin;  $rs[]    = implode(' ',array_slice($numArr,0,$combineLen));  $j        = 1;  while(strrev($find) != $bin) {    $k = explode('10',$find,2);    $find = $find{0} === '0' ? strrev($k[0]).'01'.$k[1] : $k[0].'01'.$k[1];    for($i=0;$i<$numCt;$i++) $rs[$j] .=  $find[$i] ?  $numArr[$i] . " " : '';    $j++;  }  return $rs;}
[解决办法]
PHP code
[User:root Time:21:21:46 Path:/home/liangdong/php]$ php permutation.php Total time used : 9738642ms[User:root Time:21:21:56 Path:/home/liangdong/php]$ cat permutation.php <?php$beg_time = microtime(true);$beg_time *= 1000 * 1000;$table = range(1, 33);$temp = array();$fp = null;function _get_permutations($index, $num) {        global $temp;        global $total;        global $table;        global $fp;        if ($num == $total) {                global $perms;                fwrite($fp, json_encode($temp) . PHP_EOL);                return;        }        for ($ndx = $index; 33 - $ndx + $num >= $total; ++ $ndx) {                $temp[$num] = $table[$ndx];                _get_permutations($ndx + 1, $num + 1);        }}function get_permutations($n = 6) {        global $total;        global $perms;        global $fp;        if ($n <= 0 && $n > 33) {                return false;        }        $total = $n;        $fp = fopen("data.txt", "w");        _get_permutations(0, 0);        fclose($fp);        return true;}get_permutations();$end_time = microtime(true);$end_time *= 1000 * 1000;echo "Total time used : " . ($end_time - $beg_time) . "ms" . PHP_EOL;?>