起风网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
1 $arr = [ 2 1=>['id'=>1,'name'=>'父1','father'=>NULL], 3 2=>['id'=>2,'name'=>'父2','father'=>NULL], 4 3=>['id'=>3,'name'=>'父3','father'=>NULL], 5 4=>['id'=>4,'name'=>'儿1-1','father'=>1], 6 5=>['id'=>5,'name'=>'儿1-2','father'=>1], 7 6=>['id'=>6,'name'=>'儿1-3','father'=>1], 8 7=>['id'=>7,'name'=>'儿2-1','father'=>2], 9 8=>['id'=>8,'name'=>'儿2-1','father'=>2],10 9=>['id'=>9,'name'=>'儿3-1','father'=>3],11 10=>['id'=>10,'name'=>'儿3-1-1','father'=>9],12 11=>['id'=>11,'name'=>'儿1-1-1','father'=>4],13 12=>['id'=>12,'name'=>'儿2-1-1','father'=>7],14 ];15 function generateTree($items){16 $tree = array();17 foreach($items as $item){18 if(isset($items[$item['father']])){19 $items[$item['father']]['son'][] = &$items[$item['id']]; 20 }else{21 $tree[] = &$items[$item['id']];22 }23 }24 return $tree;25 }26 $tree = generateTree($arr);27 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(使用递归获取数据)
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:
分析:
利用了递归,数组的key值与id值可以不相同,最后以顺序的结构输出数组
优点:方便遍历,查找父子元素
缺点:php不擅长递归,数据量大的情况下效率会显著降低
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