帮助重构PHP代码

我遇到了一些麻烦实施劳勒的算法，但由于SO和200美誉的赏金，我终于成功地写入工作实现：帮助重构PHP代码

Lawler's Algorithm Implementation Assistance

我觉得我是在用虽然有太多的变量和循环，但我试图重构代码。它应该更简单，更短，但仍然可读。

为此做一个类是否有意义？任何与重构这段代码的建议，甚至帮助表示欢迎：

<?php 

/* 
* @name Lawler's algorithm PHP implementation 
* @desc This algorithm calculates an optimal schedule of jobs to be 
*  processed on a single machine (in reversed order) while taking 
*  into consideration any precedence constraints. 
* @author Richard Knop 
* 
*/ 

$jobs = array(1 => array('processingTime' => 2, 
         'dueDate'  => 3), 
       2 => array('processingTime' => 3, 
         'dueDate'  => 15), 
       3 => array('processingTime' => 4, 
         'dueDate'  => 9), 
       4 => array('processingTime' => 3, 
         'dueDate'  => 16), 
       5 => array('processingTime' => 5, 
         'dueDate'  => 12), 
       6 => array('processingTime' => 7, 
         'dueDate'  => 20), 
       7 => array('processingTime' => 5, 
         'dueDate'  => 27), 
       8 => array('processingTime' => 6, 
         'dueDate'  => 40), 
       9 => array('processingTime' => 3, 
         'dueDate'  => 10)); 
// precedence constrainst, i.e job 2 must be completed before job 5 etc 
$successors = array(2=>5, 
        7=>9); 
$n = count($jobs); 
$optimalSchedule = array(); 

for ($i = $n; $i >= 1; $i--) { 

    // jobs not required to precede any other job 
    $arr = array(); 
    foreach ($jobs as $k => $v) { 

     if (false === array_key_exists($k, $successors)) { 
      $arr[] = $k; 
     } 

    } 

    // calculate total processing time 
    $totalProcessingTime = 0; 
    foreach ($jobs as $k => $v) { 
     if (true === array_key_exists($k, $arr)) { 
      $totalProcessingTime += $v['processingTime']; 
     } 
    } 

    // find the job that will go to the end of the optimal schedule array 
    $min = null; 
    $x = 0; 
    $lastKey = null; 
    foreach($arr as $k) { 
     $x = $totalProcessingTime - $jobs[$k]['dueDate']; 
     if (null === $min || $x < $min) { 
      $min = $x; 
      $lastKey = $k; 
     } 
    } 

    // add the job to the optimal schedule array 
    $optimalSchedule[$lastKey] = $jobs[$lastKey]; 
    // remove job from the jobs array 
    unset($jobs[$lastKey]); 
    // remove precedence constraint from the successors array if needed 
    if (true === in_array($lastKey, $successors)) { 
     foreach ($successors as $k => $v) { 
      if ($lastKey === $v) { 
       unset($successors[$k]); 
      } 
     } 
    } 

} 

// reverse the optimal schedule array and preserve keys 
$optimalSchedule = array_reverse($optimalSchedule, true); 

// add tardiness to the array 
$i = 0; 
foreach ($optimalSchedule as $k => $v) { 
    $optimalSchedule[$k]['tardiness'] = 0; 
    $j = 0; 
    foreach ($optimalSchedule as $k2 => $v2) { 
     if ($j <= $i) { 
      $optimalSchedule[$k]['tardiness'] += $v2['processingTime']; 
     } 
     $j++; 
    } 
    $i++; 
} 

echo '<pre>'; 
print_r($optimalSchedule); 
echo '</pre>';

来源

2010-03-21 Richard Knop

因此，当您询问特定问题时效果最佳。那么，你究竟想知道什么？如果将代码抽象为一系列类或函数是有意义的？是的，几乎总是。 – middus 2010-03-21 22:42:56

我想使它成为一个类。当所有必要的变量都封装为类成员时，我发现重构算法更容易，而不是记住每次提取方法时必须传入和传出的值。

您应该将输入设置为构造函数中的算法，然后使用通用的execute方法。这将允许您更容易地符合命令和策略模式。

将所有循环和条件主体变为单独的受保护函数。通过适当的命名，这将极大地提高可读性，并通过继承来更改算法。

来源

2010-03-21 22:45:54 Duncan

帮助重构PHP代码

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