最近学了PHP,又写了个24点计算器,采用2个页面。一个输入,一个输出。

<html>
 <body>
 <title>24点计算器</title>
 <form action="2.php" method="post">
第一个<input type="text" name="a">
第二个<input type="text" name="b">
第三个<input type="text" name="c">
第四个<input type="text" name="d">
 <input type="submit">
</form>
 </body>
 </html> 
<html>
 <body>
 <title>计算结果</title>
<?php  
error_reporting(E_ALL ^ E_NOTICE);   //关闭提醒

    $a = $_POST["a"];                //获得输入
    $b = $_POST["b"];
    $c = $_POST["c"];
    $d = $_POST["d"];
  
  set_time_limit(0);   
  $values = array($a, $b, $c, $d);   //丢数组里
  $result = 24;  
    
  $list = array();  
    
  echo "<pre>";   
  makeValue($values);   
  print_r($list);  
    
  function makeValue($values, $set=array())   
  {   
      $words = array("+", "-", "*", "/");   
      if(sizeof($values)==1)   
      {   
          $set[] = array_shift($values);   
          return makeSpecial($set);   
      }   
        
      foreach($values as $key=>$value)   
      {   
          $tmpValues = $values;   
          unset($tmpValues[$key]);   
          foreach($words as $word)   
          {   
              makeValue($tmpValues, array_merge($set, array($value, $word)));   
          }   
      }   
  }   

  function makeSpecial($set)   
  {   
      $size = sizeof($set);  
    
      if($size<=3 || !in_array("/", $set) && !in_array("*", $set))   
      {   
          return makeResult($set);   
      }  
    
      for($len=3; $len<$size-1; $len+=2)   
      {   
          for($start=0; $start<$size-1; $start+=2)   
          {   
              if(!($set[$start-1]=="*" || $set[$start-1]=="/" || $set[$start+$len]=="*" || $set[$start+$len]=="/"))   
                  continue;   
              $subSet = array_slice($set, $start, $len);   
              if(!in_array("+", $subSet) && !in_array("-", $subSet))   
                  continue;   
              $tmpSet = $set;   
              array_splice($tmpSet, $start, $len-1);   
              $tmpSet[$start] = "(".implode("", $subSet).")";   
              makeSpecial($tmpSet);   
          }   
      }   
  }  
    
  function makeResult($set)   
  {   
      global $result, $list;   
      $str = implode("", $set);   
      @eval("\$num=$str;");   
      if($num==$result && !in_array($str, $list))   
      $list[] = $str;   
  }  
  echo "<pre>";
  ?>  

  <!-- 返回 -->
<form action="1.php" method="post">
 回到上一页:
<input type="submit">
</form>
   </body>
 </html>