腾讯-1亿个数据取前1万大的整数-题解答

以下是代码片段：
< ?php 
  
/** 
 * 交换两个数据的值 
 * 
 * @param unknown_type $x 
 * @param unknown_type $y 
 */ 
function swap(&$x,&$y) 
{ 
    $c = $x; 
    $x = $y; 
    $y = $c;     
} 
  
/** 
 * 快速排序函数 
 * 
 */ 
function quicksort( $arr, $l = 0 , $r = NULL ) { 
    static $list = array(); 
    if( $r == NULL ) 
        $list = $arr; 
  
    if( $r == NULL ) 
        $r = count($list)-1; 
  
    $i = $l; 
    $j = $r; 
  
    $tmp = $list[(int)( ($l+$r)/2 )]; 
    do { 
        while( $list[$i] < $tmp ) 
            $i++; 
  
        while( $tmp < $list[$j] ) 
            $j--; 
  
        if( $i <= $j )  
        { 
           swap($list[$i],$list[$j]); 
           $i++; 
           $j--; 
        } 
    }while( $i <= $j ); 
  
    if( $l < $j ) 
        quicksort(NULL, $l, $j); 
  
    if( $i < $r ) 
        quicksort(NULL, $i, $r); 
  
    return $list; 
} 
  
/** 
 * 计算运行时间类 
 * 
 */ 
class timer  
{  
    var $StartTime = 0;  
    var $StopTime = 0;  
    var $TimeSpent = 0;  
    function start() 
    {  
      $this->StartTime = microtime();  
    }  
    function stop() 
    {  
      $this->StopTime = microtime();  
    }  
    function spent()  
    {  
      if ($this->TimeSpent) 
      {  
               return $this->TimeSpent;  
      } 
      else 
      {  
           $StartMicro = substr($this->StartTime,0,10);  
           $StartSecond = substr($this->StartTime,11,10);  
           $StopMicro = substr($this->StopTime,0,10);  
           $StopSecond = substr($this->StopTime,11,10);  
           $start = doubleval($StartMicro) + $StartSecond;  
           $stop = doubleval($StopMicro) + $StopSecond;  
           $this->TimeSpent = $stop - $start;  
           return substr($this->TimeSpent,0,8)."秒";  
      }  
    } 
}//end class timer; 
  
//构造1000000个数据的数组 
// $number 拆分1000*1000数组 
// $number2 1000000个数据的1维数组 
  
for($i=0;$i< = 999;$i++) 
{ 
    for($j=0;$j<=999;$j++) 
    { 
        $number2[] = $number[$i][$j] = rand(0,10000); 
    } 
} 
  
$timer = new timer;  
$timer->start();  
  
$max = array(); 
foreach ($number as $list) 
{ 
    $maxvalue = 0; 
    foreach ($list as $value) 
    { 
        if($maxvalue < $value) 
        { 
            $maxvalue = $value; 
        } 
    } 
    $max[] = $maxvalue; 
} 
  
  
$max = quicksort($max,0); 
for($i=0;$i < 1000000;$i++) 
{ 
        //如果数组的数据大于max最小值，则从大到小对比其他数据 
    if($number2[$i] >$max[0]) 
    { 
        for ($k=999;$k>=0;$k--) 
        { 
            if($max[$k] < $number2[$i]) 
            { 
                    //替换数据 
                $max[$k] = $number2[$i]; 
                break; 
            } 
        } 
    } 
} 
  
$timer->stop();  
  
echo ’第一次排序时间:’.$timer->spent(); 
/*print_r($max);*/ 
$timer2 = new timer(); 
$timer2->start(); 
quicksort($number2,0); 
$timer2->stop(); 
echo ’第2次排序时间:’.$timer2->spent(); 
/*print_r($number2);*/