PHP迭代与递归实现无限级分类

更新时间：2020-03-24 02:21:02 作者：startmvc

无限级分类是开发中常见的情况,因此本文对常见的无限极分类算法进行总结归纳.1.循环迭

无限级分类是开发中常见的情况,因此本文对常见的无限极分类算法进行总结归纳.

1.循环迭代实现


$arr = [
 1=>['id'=>1,'name'=>'父1','father'=>NULL],
 2=>['id'=>2,'name'=>'父2','father'=>NULL],
 3=>['id'=>3,'name'=>'父3','father'=>NULL],
 4=>['id'=>4,'name'=>'儿1-1','father'=>1],
 5=>['id'=>5,'name'=>'儿1-2','father'=>1],
 6=>['id'=>6,'name'=>'儿1-3','father'=>1],
 7=>['id'=>7,'name'=>'儿2-1','father'=>2],
 8=>['id'=>8,'name'=>'儿2-1','father'=>2],
 9=>['id'=>9,'name'=>'儿3-1','father'=>3],
 10=>['id'=>10,'name'=>'儿3-1-1','father'=>9],
 11=>['id'=>11,'name'=>'儿1-1-1','father'=>4],
 12=>['id'=>12,'name'=>'儿2-1-1','father'=>7],
];
function generateTree($items){
 $tree = array();
 foreach($items as $item){
 if(isset($items[$item['father']])){
 $items[$item['father']]['son'][] = &$items[$item['id']]; 
 }else{
 $tree[] = &$items[$item['id']];
 }
 }
 return $tree;
}
$tree = generateTree($arr);
print_r(json_encode($tree));

输出:

分析:

这个算法利用了循环迭代,将线性结构按照父子关系以树形结构输出,算法的关键在于使用了引用.

优点:速度快,效率高.

缺点:数组的key值必须与id值相同,不便于取出数据(同样使用迭代获取数据)

2.递归实现


$arr = [
 0=>['id'=>1,'name'=>'父1','father'=>0],
 1=>['id'=>2,'name'=>'父2','father'=>0],
 2=>['id'=>3,'name'=>'父3','father'=>0],
 3=>['id'=>4,'name'=>'儿1-1','father'=>1],
 4=>['id'=>5,'name'=>'儿1-2','father'=>1],
 5=>['id'=>6,'name'=>'儿1-3','father'=>1],
 6=>['id'=>7,'name'=>'儿2-1','father'=>2],
 7=>['id'=>8,'name'=>'儿2-1','father'=>2],
 8=>['id'=>9,'name'=>'儿3-1','father'=>3],
 9=>['id'=>10,'name'=>'儿3-1-1','father'=>9],
 10=>['id'=>11,'name'=>'儿1-1-1','father'=>4],
 11=>['id'=>12,'name'=>'儿2-1-1','father'=>7],
];
function generateTree($arr,$id,$step){
 static $tree=[];
 foreach($arr as $key=>$val) {
 if($val['father'] == $id) {
 $flg = str_repeat('└―',$step);
 $val['name'] = $flg.$val['name'];
 $tree[] = $val;
 generateTree($arr , $val['id'] ,$step+1);
 }
 }
 return $tree;
}
$tree = generateTree($arr,0,0);
foreach ($tree as $val){
 echo $val['name'].'<br>';
}

输出: