php数字游戏计算24算法_php实例

<br><!--?php <BR-->/** <br>* A 24 maker <br>* @version 1.0.0 <br>* @author laruence<laruence at="" yahoo.com.cn=""> <br>* @copyright (c) 2009 http://www.laruence.com <br>*/ <br>class TwentyFourCal { <br>public $needle = 24; <br>public $precision = '1e-6'; <br>function TwentyFourCal() { <br>} <br>private function notice($mesg) { <br>var_dump($mesg); <br>} <br>/** <br>* 取得用户输入方法 <br>*/ <br>public function calculate($operants = array()) { <br>try { <br>$this->search($operants, 4); <br>} catch (Exception $e) { <br>$this->notice($e->getMessage()); <br>return; <br>} <br>$this->notice('can\'t compute!'); <br>return; <br>} <br>/** <br>* 求24点算法PHP实现 <br>*/ <br>private function search($expressions, $level) { <br>if ($level == 1) { <br>$result = 'return ' . $expressions[0] . ';'; <br>if ( abs(eval($result) - $this->needle) <= $this->precision) { <br>throw new Exception($expressions[0]); <br>} <br>} <br>for ($i=0;$i<$level;$i++) { <br>for ($j=$i+1;$j<$level;$j++) { <br>$expLeft = $expressions[$i]; <br>$expRight = $expressions[$j]; <br>$expressions[$j] = $expressions[$level - 1]; <br>$expressions[$i] = '(' . $expLeft . ' + ' . $expRight . ')'; <br>$this->search($expressions, $level - 1); <br>$expressions[$i] = '(' . $expLeft . ' * ' . $expRight . ')'; <br>$this->search($expressions, $level - 1); <br>$expressions[$i] = '(' . $expLeft . ' - ' . $expRight . ')'; <br>$this->search($expressions, $level - 1); <br>$expressions[$i] = '(' . $expRight . ' - ' . $expLeft . ')'; <br>$this->search($expressions, $level - 1); <br>if ($expLeft != 0) { <br>$expressions[$i] = '(' . $expRight . ' / ' . $expLeft . ')'; <br>$this->search($expressions, $level - 1); <br>} <br>if ($expRight != 0) { <br>$expressions[$i] = '(' . $expLeft . ' / ' . $expRight . ')'; <br>$this->search($expressions, $level - 1); <br>} <br>$expressions[$i] = $expLeft; <br>$expressions[$j] = $expRight; <br>} <br>} <br>return false; <br>} <br>function __destruct() { <br>} <br>} <br>/* demo */ <br>$tf = new TwentyFourCal(); <br>$tf->calculate( array(4,8,8,8) ); <br>?> <br>                    </laruence>