关于递归算法的讨论

 array('id'=>'1','parentid'=>0,'name'=>'一级栏目一'), * 2 => array('id'=>'2','parentid'=>0,'name'=>'一级栏目二'), * 3 => array('id'=>'3','parentid'=>1,'name'=>'二级栏目一'), * 4 => array('id'=>'4','parentid'=>1,'name'=>'二级栏目二'), * 5 => array('id'=>'5','parentid'=>2,'name'=>'二级栏目三'), * 6 => array('id'=>'6','parentid'=>3,'name'=>'三级栏目一'), * 7 => array('id'=>'7','parentid'=>3,'name'=>'三级栏目二') * ) */ public function __construct($arr=array()){ $this->arr = $arr; $this->ret = ''; return is_array($arr); } /** * 得到父级数组 * @param int * @return array */ public function get_parent($myid){ $newarr = array(); if(!isset($this->arr[$myid])) return false; $pid = $this->arr[$myid]['parentid']; $pid = $this->arr[$pid]['parentid']; if(is_array($this->arr)) { foreach($this->arr as $id => $a) { if($a['parentid'] == $pid) $newarr[$id] = $a; } } return $newarr; } /** * 得到子级数组 * @param int * @return array */ public function get_child($myid) { $a = $newarr = array(); if(is_array($this->arr)) { foreach($this->arr as $id => $a) { if($a['parentid'] == $myid) $newarr[$id] = $a; } } return $newarr ? $newarr : false; } /** * 得到当前位置数组 * @param int * @return array */ public function get_pos($myid,&$newarr) { $a = array(); if(!isset($this->arr[$myid])) return false; $newarr[] = $this->arr[$myid]; $pid = $this->arr[$myid]['parentid']; if(isset($this->arr[$pid])) { $this->get_pos($pid,$newarr); } if(is_array($newarr)) { krsort($newarr); foreach($newarr as $v) { $a[$v['id']] = $v; } } return $a; } /** * 得到树型结构 * @param int ID，表示获得这个ID下的所有子级 * @param string 生成树型结构的基本代码，例如："\$spacer\$name" * @param int 被选中的ID，比如在做树型下拉框的时候需要用到 * @return string */ public function get_tree($myid, $str, $sid = 0, $adds = '', $str_group = '') { $number=1; $child = $this->get_child($myid); print_r($child); if(is_array($child)) { $total = count($child); foreach($child as $id=>$value) { $j=$k=''; if($number==$total) { $j .= $this->icon[2]; //如果是最后一个子级使用└ }else { $j .= $this->icon[1]; $k = $adds ? $this->icon[0] : ''; } $spacer = $adds ? $adds.$j : ''; //├ $selected = $id==$sid ? 'selected' : ''; //下拉选择 @extract($value);//此方法为下面的字符变量赋上相应的键值 $nstr,$str_group $parentid == 0 && $str_group ? eval("\$nstr = \"$str_group\";") : eval("\$nstr = \"$str\";"); $this->ret .= $nstr; $nbsp = $this->nbsp; $this->get_tree($id, $str, $sid, $adds.$k.$nbsp,$str_group); //如果子集是数组，递归调用 $number++; } } return $this->ret; }}$arr= array( 1 => array('id'=>'1','parentid'=>0,'name'=>'世界'), 3 => array('id'=>'3','parentid'=>1,'name'=>'中国'), 4 => array('id'=>'4','parentid'=>1,'name'=>'美国'), 5 => array('id'=>'5','parentid'=>3,'name'=>'湖南'), 6 => array('id'=>'6','parentid'=>3,'name'=>'北京'), 7 => array('id'=>'7','parentid'=>4,'name'=>'纽约'), 7 => array('id'=>'7','parentid'=>5,'name'=>'长沙') );$tree = new tree($arr);$str = "
\$spacer\$name
";echo $tree->get_tree(0,$str);?>

 array('id'=>'1','parentid'=>0,'name'=>'一级栏目一'), * 2 => array('id'=>'2','parentid'=>0,'name'=>'一级栏目二'), * 3 => array('id'=>'3','parentid'=>1,'name'=>'二级栏目一'), * 4 => array('id'=>'4','parentid'=>1,'name'=>'二级栏目二'), * 5 => array('id'=>'5','parentid'=>2,'name'=>'二级栏目三'), * 6 => array('id'=>'6','parentid'=>3,'name'=>'三级栏目一'), * 7 => array('id'=>'7','parentid'=>3,'name'=>'三级栏目二') * ) */ public function __construct($arr=array()){ $this->arr = $arr; $this->ret = ''; return is_array($arr); } /** * 得到父级数组 * @param int * @return array */ public function get_parent($myid){ $newarr = array(); if(!isset($this->arr[$myid])) return false; $pid = $this->arr[$myid]['parentid']; $pid = $this->arr[$pid]['parentid']; if(is_array($this->arr)) { foreach($this->arr as $id => $a) { if($a['parentid'] == $pid) $newarr[$id] = $a; } } return $newarr; } /** * 得到子级数组 * @param int * @return array */ public function get_child($myid) { $a = $newarr = array(); if(is_array($this->arr)) { foreach($this->arr as $id => $a) { if($a['parentid'] == $myid) $newarr[$id] = $a; } } return $newarr ? $newarr : false; } /** * 得到当前位置数组 * @param int * @return array */ public function get_pos($myid,&$newarr) { $a = array(); if(!isset($this->arr[$myid])) return false; $newarr[] = $this->arr[$myid]; $pid = $this->arr[$myid]['parentid']; if(isset($this->arr[$pid])) { $this->get_pos($pid,$newarr); } if(is_array($newarr)) { krsort($newarr); foreach($newarr as $v) { $a[$v['id']] = $v; } } return $a; } /** * 得到树型结构 * @param int ID，表示获得这个ID下的所有子级 * @param string 生成树型结构的基本代码，例如："\$spacer\$name" * @param int 被选中的ID，比如在做树型下拉框的时候需要用到 * @return string */ public function get_tree($myid, $str, $sid = 0, $adds = '', $str_group = '') { $number=1; $child = $this->get_child($myid); print_r($child); if(is_array($child)) { $total = count($child); foreach($child as $id=>$value) { $j=$k=''; if($number==$total) { $j .= $this->icon[2]; //如果是最后一个子级使用└ }else { $j .= $this->icon[1]; $k = $adds ? $this->icon[0] : ''; } $spacer = $adds ? $adds.$j : ''; //├ $selected = $id==$sid ? 'selected' : ''; //下拉选择 @extract($value);//此方法为下面的字符变量赋上相应的键值 $nstr,$str_group $parentid == 0 && $str_group ? eval("\$nstr = \"$str_group\";") : eval("\$nstr = \"$str\";"); $this->ret .= $nstr; $nbsp = $this->nbsp; $this->get_tree($id, $str, $sid, $adds.$k.$nbsp,$str_group); //如果子集是数组，递归调用 $number++; } } return $this->ret; }}$arr= array( 1 => array('id'=>'1','parentid'=>0,'name'=>'世界'), 3 => array('id'=>'3','parentid'=>1,'name'=>'中国'), 4 => array('id'=>'4','parentid'=>1,'name'=>'美国'), 5 => array('id'=>'5','parentid'=>3,'name'=>'湖南'), 6 => array('id'=>'6','parentid'=>3,'name'=>'北京'), 7 => array('id'=>'7','parentid'=>4,'name'=>'纽约'), 7 => array('id'=>'7','parentid'=>5,'name'=>'长沙') );$tree = new tree($arr);$str = "
\$spacer\$name
";echo $tree->get_tree(0,$str);?>