PHP汉诺塔问题的递归算法实现和迭代算法实现

实现代码

程序代码地址：https://github.com/ParrySMS/Exp/tree/master/ProLang/hannota

递归法 hannoRec.php

<?php
/**
 * Created by PhpStorm.
 * User: L
 * Date: 2018-4-15
 * Time: 2:07
 */

/** 递归实现
 * @param $id //盘子编号
 * @param $first //起点柱子
 * @param $middle //中介柱子
 * @param $end //终点柱子
 */
function hanRec($id, $first, $middle, $end,$counter)
{
    if ($id == 1) {
        move(1,$first,$end,$counter);
    } else {
        hanRec($id-1,$first,$end,$middle,$counter);
        move($id,$first,$end,$counter);
        $counter++;
        hanRec($id-1,$middle,$first,$end,$counter);
    }
}

function move($id,$from,$to,$counter){
    global $counter;
    $counter++;
   // echo "step: $counter, level $id from $from move to $to, <br/>";
}

---

迭代法 hannoIter

<?php

/**
 * Created by PhpStorm.
 * User: L
 * Date: 2018-4-17
 * Time: 2:38
 */
class Params{ //定义一个对象来保存参数状态
    public $id;
    public $num;
    public $first;
    public $middle;
    public $end;
    public $counter;

    /**
     * Params constructor.
     * @param $num
     * @param $first
     * @param $middle
     * @param $end
     * @param $counter
     */
    public function __construct($id,$num, $first, $middle, $end, $counter)
    {
        $this->id = $id;
        $this->num = $num;
        $this->first = $first;
        $this->middle = $middle;
        $this->end = $end;
        $this->counter = $counter;
    }

}


function hanIter($id,$num, $first, $middle, $end, $counter)
{
    $stack =init($id,$num, $first, $middle, $end, $counter);
    while($stack){
        //出栈
        $action = array_pop($stack);
       // var_dump($action);
        if($action->num ==1){
            move($action->id,$action->first,$action->end,$action->counter);
        }else{
            //入栈
            $next_stack = init($action->id,$action->num,$action->first, $action->middle, $action->end, $action->counter);
            $stack=array_merge($stack,$next_stack);
        }
    }

}

/** 入栈操作
 * @param $id //需要移动的盘子
 * @param $num //移动该盘子需要挪动的总盘子数量
 * @param $first
 * @param $middle
 * @param $end
 * @param $counter
 * @return array
 */
function init($id,$num,$first, $middle, $end, $counter)
{
    unset($stack);
    //注意入站出站顺序
    $stack = array();
    //第一次回调
    $stack[] =new Params($id-1,$num-1,$middle,$first,$end,$counter);
    //第二次回调
    $stack[] =new Params($id,1,$first, $middle, $end, $counter);
    //第三次回调
    $stack[] =new Params($id-1,$num-1,$first,$end,$middle,$counter);
    return $stack;

}

/** 若在测试用例中，由于两个文件都有此 move函数，函数重名，注释掉其中一个即可 

function move($id,$from,$to,$counter){
    global $counter;
    $counter++;
   // echo "step: $counter, level $id from $from move to $to, <br/>";
}

**/

---

执行时间测试脚本 test.php

<?php
/**
 * Created by PhpStorm.
 * User: L
 * Date: 2018-4-17
 * Time: 2:18
 */

require "hannoRec.php";
require "hannoIter.php";



define('TIMES', 100);
define('NUM', 10);

function rowTable()
{
    unset($row);
    $row = array();

    for ($i = 0; $i < TIMES; $i++) {
    $row = getSortRow($row);
    }

    foreach ($row as $r) {
        print <<< TR
 <tr>
       <td>$r->iter</td>
       <td>$r->rec</td>
    </tr>
TR;
    }
}

function getSortRow(array $row)
{
    $num = NUM;
    $counter= 0;
    $stime = microtime(true);
    hanIter($num, $num, 'A', 'B', 'C', $counter);
    $etime = microtime(true);
    $iterTime = 1000 * ($etime - $stime);

//    echo "<br/>";
    $counter = 0;
    $num = NUM;
    $stime = microtime(true);
    hanRec($num, 'A', 'B', 'C', $counter);
    $etime = microtime(true);
    $recTime = 1000 * ($etime - $stime);

    $row[] = (object)["iter" => $iterTime, "rec" => $recTime];
    return $row;
}


?>

<table border="1">
    <tr>
        <th>迭代 Iter/ms</th>
        <th>递归 Rec/ms</th>
    </tr>
    <?php rowTable(); ?>
</table>

参考

迭代法思路：https://wenku.baidu.com/view/dce79165b0717fd5360cdcdb.html