<?php
class Search_Method
{
  //無向圖的數(shù)組描述
  private $dfs_save;
  //全局記錄數(shù)組
  private $arr;
  //控制分支-
  private $k = 0;
  public function __construct()
  {
    $this->dfs_save = array(
      array(0,1,1,1,0,0,0,0,0),
      array(1,0,0,0,1,0,0,0,0),
      array(1,0,0,0,0,1,0,0,0),
      array(1,0,0,0,0,0,1,0,0),
      array(0,1,0,0,0,1,0,0,1),
      array(0,0,1,0,1,0,0,1,0),
      array(0,0,0,1,0,0,0,0,0),
      array(0,0,0,0,0,1,0,0,0),
      array(0,0,0,0,1,0,0,0,0),
    );
    $this->arr = array();
  }
  //深度優(yōu)先搜索的遞歸實(shí)現(xiàn)方法
  public function dfs($v)
  {
    //對(duì)頂點(diǎn)做一些操作
    echo str_repeat("-",$this->k);
    echo 'V'.($v+1).'<br>';
    //記錄已訪問的頂點(diǎn)
    $this->arr[]= $v;
    //查找與頂點(diǎn)相連接的頂點(diǎn)，如果存在就繼續(xù)深度優(yōu)先搜索
    for($i=0;$i<9;$i++)
    {
      if(!in_array($i,$this->arr)&&$this->dfs_save[$v][$i]==1)
      {
        $this->k++;
        $this->dfs($i);
      }
    }
    $this->k--;
    return;
  }
}
?>

V1
-V2
--V5
---V6
----V3
----V8
---V9
-V4
--V7