PHP迭代与递归实现无限级分类

2024-05-04 22:45:42

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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: