用php实现flody算法输出,该怎么解决

用php实现flody算法输出
以下是我实现的flody算法，可是我在写output()函数时输不出来结果，请高手帮帮忙，写出来，不尽感激！
/**
* PHP 实现图邻接矩阵
*
* @author zhaojiangwei
* @since 2011/10/31 17:23
*/

class MGraph{
private $vexs; //顶点数组
private $arc; //边邻接矩阵,即二维数组
private $arcData; //边的数组信息
private $direct; //图的类型(无向或有向)
private $infinity = 65535;//代表无穷,即两点无连接,建带权值的图时用,本示例不带权值


public function MGraph($vexs, $arc, $direct = 0){
$this->vexs = $vexs;
$this->arcData = $arc;
$this->direct = $direct;
$this->initalizeArc();
$this->createArc();
}

private function initalizeArc(){
foreach($this->vexs as $value){
foreach($this->vexs as $cValue){
$this->arc[$value][$cValue] = ($value == $cValue ? 0 : $this->infinity);
}
}
}

//创建图 $direct:0表示无向图,1表示有向图
private function createArc(){
foreach($this->arcData as $key=>$value){
$strArr = str_split($key);
$first = $strArr[0];
$last = $strArr[1];
$this->arc[$first][$last] = $value;
if(!$this->direct){
$this->arc[$last][$first] = $value;
}
}
}

//floyd算法
public function floyd(){
$path = array();//路径数组
$distance = array();//距离数组

foreach($this->arc as $key=>$value){
foreach($value as $k=>$v){
$path[$key][$k] = $k;
$distance[$key][$k] = $v;
}
}

for($j = 0; $j < count($this->vexs); $j ++){
for($i = 0; $i < count($this->vexs); $i ++){
for($k = 0; $k < count($this->vexs); $k ++){
if($distance[$this->vexs[$i]][$this->vexs[$k]] > $distance[$this->vexs[$i]][$this->vexs[$j]] + $distance[$this->vexs[$j]][$this->vexs[$k]]){