从数据表里取得一组二维数组，每个元素有键为 id 和 pid 的值，在不使用递归的情况下，如何按照其 pid 的值将元素移入到相应 id 元素中成为其子元素？
<code>array(6) {
[0] => array(3) {
["id"] => "21"
["pid"] => "0"
["name"] => "aaa"
}
[1] => array(3) {
["id"] => "22"
["pid"] => "0"
["name"] => "bbb"
}
[2] => array(3) {
["id"] => "23"
["pid"] => "0"
["name"] => "ccc"
}
[3] => array(3) {
["id"] => "24"
["pid"] => "23"
["name"] => "ddd"
}
[4] => array(3) {
["id"] => "25"
["pid"] => "23"
["name"] => "eee"
}
[5] => array(3) {
["id"] => "26"
["pid"] => "22"
["name"] => "fff"
}
}
</code>重新排列为
<code>array(3) {
[0] => array(3) {
["id"] => "21"
["pid"] => "0"
["name"] => "aaa"
}
[1] => array(4) {
["id"] => "22"
["pid"] => "0"
["name"] => "bbb"
["child"]=> array(1) {
[0] => array(3) {
["id"] => "26"
["pid"] => "22"
["name"] => "fff"
}
}
}
[2] => array(4) {
["id"] => "23"
["pid"] => "0"
["name"] => "ccc"
["child"]=> array(2) {
[0] => array(3) {
["id"] => "24"
["pid"] => "23"
["name"] => "ddd"
}
[1] => array(3) {
["id"] => "25"
["pid"] => "23"
["name"] => "eee"
}
}
}
}
</code>涉及层级关系只有两层。
从数据表里取得一组二维数组，每个元素有键为 id 和 pid 的值，在不使用递归的情况下，如何按照其 pid 的值将元素移入到相应 id 元素中成为其子元素？
<code>array(6) {
[0] => array(3) {
["id"] => "21"
["pid"] => "0"
["name"] => "aaa"
}
[1] => array(3) {
["id"] => "22"
["pid"] => "0"
["name"] => "bbb"
}
[2] => array(3) {
["id"] => "23"
["pid"] => "0"
["name"] => "ccc"
}
[3] => array(3) {
["id"] => "24"
["pid"] => "23"
["name"] => "ddd"
}
[4] => array(3) {
["id"] => "25"
["pid"] => "23"
["name"] => "eee"
}
[5] => array(3) {
["id"] => "26"
["pid"] => "22"
["name"] => "fff"
}
}
</code>重新排列为
<code>array(3) {
[0] => array(3) {
["id"] => "21"
["pid"] => "0"
["name"] => "aaa"
}
[1] => array(4) {
["id"] => "22"
["pid"] => "0"
["name"] => "bbb"
["child"]=> array(1) {
[0] => array(3) {
["id"] => "26"
["pid"] => "22"
["name"] => "fff"
}
}
}
[2] => array(4) {
["id"] => "23"
["pid"] => "0"
["name"] => "ccc"
["child"]=> array(2) {
[0] => array(3) {
["id"] => "24"
["pid"] => "23"
["name"] => "ddd"
}
[1] => array(3) {
["id"] => "25"
["pid"] => "23"
["name"] => "eee"
}
}
}
}
</code>涉及层级关系只有两层。
我想学算法的时候应该有讲过如何把递归改成循环实现。
一般递归都可以用队列+循环来实现，你先想想，空了来写程序。
你这个本来就是该循环实现的，哪里需要递归啊……
要是看不懂 JS，C# 和 Java 看得懂不？PHP丢太久了，语法都忘了
<code>javascript</code><code>var data = [{
"id": "21",
"pid": "0",
"name": "aaa"
}, {
"id": "22",
"pid": "0",
"name": "bbb"
}, {
"id": "23",
"pid": "0",
"name": "ccc"
}, {
"id": "24",
"pid": "23",
"name": "ddd"
}, {
"id": "25",
"pid": "23",
"name": "eee"
}, {
"id": "26",
"pid": "22",
"name": "fff"
}];
var map = {}
var root = []
data.forEach(function(item) {
map[item.id] = item;
var parent = map[item.pid];
if (parent) {
parent.child = parent.child || [];
parent.child.push(item);
} else {
root.push(item);
}
});
console.log(JSON.stringify(root, null, 4));
</code>输出
<code>[
{
"id": "21",
"pid": "0",
"name": "aaa"
},
{
"id": "22",
"pid": "0",
"name": "bbb",
"child": [
{
"id": "26",
"pid": "22",
"name": "fff"
}
]
},
{
"id": "23",
"pid": "0",
"name": "ccc",
"child": [
{
"id": "24",
"pid": "23",
"name": "ddd"
},
{
"id": "25",
"pid": "23",
"name": "eee"
}
]
}
]
</code>
非常感谢诸位的解答。看了你们的答案还在消化。基础不扎实还要多学习。
自己参考了一下隔壁问题。实现的代码如下：
<code>$arr = array(
array('id'=>21, 'pid'=>0, 'name'=>'aaa'),
array('id'=>22, 'pid'=>0, 'name'=>'bbb'),
array('id'=>23, 'pid'=>0, 'name'=>'ccc'),
array('id'=>24, 'pid'=>23, 'name'=>'ddd'),
array('id'=>25, 'pid'=>23, 'name'=>'eee'),
array('id'=>26, 'pid'=>22, 'name'=>'fff'),
);
$temp=[];
foreach ($arr as $item)
{
list($id,$pid,$name) = array_values($item); // 取出数组的值并分别生成变量
if(array_key_exists($pid, $temp))
// 检查临时数组$temp中是否存在键名与$pid的值相同的键
{
$temp[$pid]['child'][]=array('id'=>$id,'pid'=>$pid,'name'=>$name);
// 如果存在则新增数组至临时数组中键名为 $pid 的子元素 child 内
}else
$temp[$id]=array('id'=>$id,'pid'=>$pid,'name'=>$name);
// 如果不存在则新增数组至临时数组中并设定键名为 $id
}
$array = array_values($temp);
// 将临时数组中以 $id 为键名的键修改为数字索引
echo "<pre class="brush:php;toolbar:false;">";
print_r($array);
</code>取值生成变量步骤有点多余，foreach 部分更新如下：
<code>foreach ($arr as $item)
{
if (array_key_exists($item['pid'], $temp))
{
$temp[$item['pid']]['child'][]=$item;
}else
$temp[$item['id']]=$item;
}
</code>
先算出每个数组的顶级pid,然后再排序下。
<code><?php
// 原本的数组, 偷个懒用JSON还原之
$arr = json_decode('[{
"id": "21",
"pid": "0",
"name": "aaa"
}, {
"id": "22",
"pid": "0",
"name": "bbb"
}, {
"id": "23",
"pid": "0",
"name": "ccc"
}, {
"id": "24",
"pid": "23",
"name": "ddd"
}, {
"id": "25",
"pid": "23",
"name": "eee"
}, {
"id": "26",
"pid": "22",
"name": "fff"
}]',TRUE);
$newArr = $rtnArr = array();
$current = array_shift($arr);
while($current){
if($current['pid']){
if(array_key_exists($current['pid'],$newArr)){
$newArr[$current['pid']]['child'][]= $current;
}else{
$newArr[$current['pid']] = array('id'=>$current['pid'],'child'=>array());
}
}else{
if(array_key_exists($current['id'],$newArr)){
array_merge($newArr[$current['id']],$current);
}else{
$newArr[$current['id']] = $current;
}
}
$current = array_shift($arr);
}
// 更新数组和子数组的排序
ksort($newArr);
foreach($newArr as $arr){
if(array_key_exists('child',$arr)){
usort($arr['child'],function($a,$b){
return $a['id'] > $b['id'] ? 1 : -1;
});
}
array_push($rtnArr,$arr);
}
// 打印
print_r($rtnArr);
?>
</code>
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