ใครมี มีตัวอย่าง code DepthFirstSearch ภาษาphp+++++++ขอดูเป็นตัวอย่างหน่อยคาบ

<?php

class state_space_graph{

    var $connected;
    var $start_state;
    var $goal_state;

    function connectedList($state,$connectedListArray){
        $a = array();
        for ($i=0;$i<count($connectedListArray);$i++){
            $cla=$connectedListArray[$i];
            if ($state==$cla{0} && $state!=$cla{1}){
                    if ( !in_array($cla{1},$a)){
                        $a[] = $cla{1};
                    }
            } elseif ($state==$cla{1} && $sate!=$cla{0}){
                    if ( !in_array($cla{0},$a)){
                        $a[] = $cla{0};
                    }
            }
        }
        return $a;
    }

    function state_space_graph($nodeList,$connectedList,$start,$goal){
        $a = explode(',',$nodeList);
        $b = explode(',',$connectedList);
        $this->start_state = $start;
        $this->goal_state = $goal;
        for ($i=0;$i<count($a);$i++){
            $this->connected[$a[$i]] = $this->connectedList($a[$i],$b);
        }
    }

    function has_children($cs,&$sl,&$nsl,&$de,&$children){
        $children = '';
                for ($i=0;$i<count($this->connected[$cs]);$i++){
                    if ( false===strpos($sl,$this->connected[$cs][$i]) &&
                        false===strpos($nsl,$this->connected[$cs][$i]) &&
                        false===strpos($de,$this->connected[$cs][$i]))
                    {
                        $children = $children.$this->connected[$cs][$i];
                    }
                }
        return strlen($children);
    }

    function remove_front(&$list){
        $list = substr($list,1);
    }

    function add_front(&$list,$cs){
        $list = $cs.$list;
    }

    function define_empty(&$list){
        $list = '';
    }

    function first_element(&$list){
        return substr($list,0,1);
    }

    function path($list){
        if (strlen($list)>0){
            $s = $list{0};
        }else{
            $s = '';
        }
        for ($i=1;$i<strlen($list);$i++){
            $s = $s.','.$list{$i};
        }
        return $s;
    }

    function pathrev($list){
        if (strlen($list)>0){
            $s = $list{0};
        }else{
            $s = '';
        }
        for ($i=1;$i<strlen($list);$i++){
            $s = $list{$i}.','.$s;
        }
        return $s;
    }

    function backtrack(){

            $cs = $this->start_state;
            $goal = $this->goal_state;
            $this->add_front($sl,$cs);
            $this->add_front($nsl,$cs);
            $this->define_empty($de);

                    echo '<table border=1 cellpadding=0 cellspacing=0 width=500>'
                    .'<tr bgcolor=silver><th>CS'.'</th><th>SL'.'</th><th>NSL'.'</th><th>DE'.'</th></tr>';

                    while (strlen($nsl) != 0) {

                            echo '<tr align=right bgcolor=gainsboro><td>&nbsp;'.$cs
                            .'</td><td>&nbsp;'.$this->path($sl)
                            .'</td><td>&nbsp;'.$this->path($nsl)
                            .'</td><td>&nbsp;'.$this->path($de).'</td></tr>';

                            if ($cs==$goal) break;
                            if ( !$this->has_children($cs,$sl,$nsl,$de,$children)){

                                    //echo '<tr><td>no have</td></tr>';
                                    while (strlen($sl) != 0 && $cs==$this->first_element($sl)){
                                            $this->add_front($de,$cs);
                                            $this->remove_front($sl);
                                            $this->remove_front($nsl);
                                            $cs = $this->first_element($nsl);
                                    }
                                    $this->add_front($sl,$cs);

                            } else{

                                    //echo '<tr><td>have</td></tr>';

                                    $this->add_front($nsl,$children);
                                    $cs = $this->first_element($nsl);
                                    $this->add_front($sl,$cs);

                            }

                    }
                    echo '</table>';

            return ($cs==$goal?$sl:false);

    }/* bracktrack function */

}

echo '<html><head><title>state space search</title></head><body>';

$g = new state_space_graph('A,B,C,D,E,F,G,H,I,J','AB,AC,AD,BE,BF,EH,EI,FJ,CF,CG','A','G');

$solution_path = $g->backtrack();

echo 'start = '.$g->start_state.'<br>';
echo 'goal = '.$g->goal_state.'<br>';
echo ($solution_path?'solution path is <b>'.$g->pathrev($solution_path).'.</b>':'don\'t found goal.');

echo '</body></html>';

?>