幫助重構PHP代碼

我遇到了一些麻煩實施勞勒的算法，但由於SO和200美譽的賞金，我終於成功地寫入工作實現：幫助重構PHP代碼

Lawler's Algorithm Implementation Assistance

我覺得我是在用雖然有太多的變量和循環，但我試圖重構代碼。它應該更簡單，更短，但仍然可讀。

爲此做一個類是否有意義？任何與重構這段代碼的建議，甚至幫助表示歡迎：

<?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>';

來源

2010-03-21 Richard Knop

因此，當您詢問特定問題時效果最佳。那麼，你究竟想知道什麼？如果將代碼抽象爲一系列類或函數是有意義的？是的，幾乎總是。 – middus 2010-03-21 22:42:56

我想使它成爲一個類。當所有必要的變量都封裝爲類成員時，我發現重構算法更容易，而不是記住每次提取方法時必須傳入和傳出的值。

您應該將輸入設置爲構造函數中的算法，然後使用通用的execute方法。這將允許您更容易地符合命令和策略模式。

將所有循環和條件主體變爲單獨的受保護函數。通過適當的命名，這將極大地提高可讀性，並通過繼承來更改算法。

來源

2010-03-21 22:45:54 Duncan

幫助重構PHP代碼

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