我们知道很多开源软件的无限分类都是采用递归的算法，但是我们知道递归即浪费时间，又浪费空间（内存）， 上次我也分享了个我自己原创的无限分类生成树的方法，一热心PHP高手网友给我提出了宝贵的建议，我测试了一下，这段代码的时间非常之短参考： http://www.oschina.net/code/snippet_98719_11296，我再次整理了一下，发现数据库查询出数据之后，我们就已经定好了键值，因而实践中，我们一般会在model中查询出格式化成主键值对应数据的形式，因而我们可以直接用这样的数据，就少了一层循环。代码也非常简洁。
原来的代码：
$tmpMap[$item[$id]] = $item;
}
foreach ($items as $item) {
if (isset($tmpMap[$item[$pid]])) {
$tmpMap[$item[$pid]][$son][] = &$tmpMap[$item[$id]];
} else {
$tree[] = &$tmpMap[$item[$id]];
}
}
unset($tmpMap);
return $tree;
}
$items1 = array(
array('id' => 1,'pid' => 0,'name' => '一级11' ),array('id' => 11,'name' => '一级12' ),array('id' => 2,'pid' => 1,'name' => '二级21' ),array('id' => 10,'pid' => 11,'name' => '二级22' ),array('id' => 3,'name' => '二级23' ),array('id' => 12,'name' => '二级24' ),array('id' => 9,'name' => '二级25' ),array('id' => 14,'name' => '二级26' ),array('id' => 4,'pid' => 9,'name' => '三级31' ),array('id' => 6,'name' => '三级32' ),array('id' => 7,'pid' => 4,'name' => '四级41' ),array('id' => 8,'name' => '四级42' ),array('id' => 5,'name' => '四级43' ),array('id' => 13,'name' => '四级44' ),array('id' => 15,'pid' => 8,'name' => '五级51' ),array('id' => 16,'name' => '五级52' ),array('id' => 17,'name' => '五级53' ),array('id' => 18,'pid' => 16,'name' => '六级64' ),);
var_dump(genTree($items1));
以下是补充：
1 => array('id' => 1,'name' => '江西省'),2 => array('id' => 2,'name' => '黑龙江省'),3 => array('id' => 3,'name' => '南昌市'),4 => array('id' => 4,'pid' => 2,'name' => '哈尔滨市'),5 => array('id' => 5,'name' => '鸡西市'),6 => array('id' => 6,'name' => '香坊区'),7 => array('id' => 7,'name' => '南岗区'),8 => array('id' => 8,'pid' => 6,'name' => '和兴路'),9 => array('id' => 9,'pid' => 7,'name' => '西大直街'),10 => array('id' => 10,'name' => '东北林业大学'),11 => array('id' => 11,'name' => '哈尔滨工业大学'),12 => array('id' => 12,'name' => '哈尔滨师范大学'),13 => array('id' => 13,'name' => '赣州市'),14 => array('id' => 14,'pid' => 13,'name' => '赣县'),15 => array('id' => 15,'name' => '于都县'),16 => array('id' => 16,'pid' => 14,'name' => '茅店镇'),17 => array('id' => 17,'name' => '大田乡'),18 => array('id' => 18,'name' => '义源村'),19 => array('id' => 19,'name' => '上坝村'),);
print_r(genTree5($items));
print_r(genTree9($items));
//后者输出格式，前者类似，只是数组键值不一样，不过不影响数据结构
/*
Array
(
[0] => Array
(
[id] => 1
[pid] => 0
[name] => 江西省
[son] => Array
(
[0] => Array
(
[id] => 3
[pid] => 1
[name] => 南昌市
)
[1] => Array
(
[id] => 13
[pid] => 1
[name] => 赣州市
[son] => Array
(
[0] => Array
(
[id] => 14
[pid] => 13
[name] => 赣县
[son] => Array
(
[0] => Array
(
[id] => 16
[pid] => 14
[name] => 茅店镇
[son] => Array
(
[0] => Array
(
[id] => 18
[pid] => 16
[name] => 义源村
)
[1] => Array
(
[id] => 19
[pid] => 16
[name] => 上坝村
)
)
)
[1] => Array
(
[id] => 17
[pid] => 14
[name] => 大田乡
)
)
)
[1] => Array
(
[id] => 15
[pid] => 13
[name] => 于都县
)
)
)
))
[1] => Array
(
[id] => 2
[pid] => 0
[name] => 黑龙江省
[son] => Array
(
[0] => Array
(
[id] => 4
[pid] => 2
[name] => 哈尔滨市
[son] => Array
(
[0] => Array
(
[id] => 6
[pid] => 4
[name] => 香坊区
[son] => Array
(
[0] => Array
(
[id] => 8
[pid] => 6
[name] => 和兴路
[son] => Array
(
[0] => Array
(
[id] => 10
[pid] => 8
[name] =>
东北林业大学
)
[1] => Array
(
[id] => 12
[pid] => 8
[name] =>
哈尔滨师范大学
)
)
)
)
)
[1] => Array
(
[id] => 7
[pid] => 4
[name] => 南岗区
[son] => Array
(
[0] => Array
(
[id] => 9
[pid] => 7
[name] => 西大直街
[son] => Array
(
[0] => Array
(
[id] => 11
[pid] => 9
[name] =>
哈尔滨工业大学
)
)
)
)
)
)
)
[1] => Array
(
[id] => 5
[pid] => 2
[name] => 鸡西市
)
))
)*/
极其简单有效！！！非常受用！
