本文介绍了如何根据平级数据构造无限级树型结构，并通过广度优先和深度优先遍历方法找到所有满足特定条件的叶子节点。通过递归函数实现无限级树的构造，广度优先遍历用于快速查找叶子节点，而深度优先遍历则用于按顺序输出指定条件的叶子节点。示例代码详细展示了整个过程。
目录
场景介绍
数据
实现
构造无限级
广度优先遍历
深度优先遍历
完整代码
场景介绍
最近接到一个需求，需要根据平级结构构造无限级树型结构，界面类似下边这样的结构
然后，还需要把所有的橙色标记的叶子节点从垂直方向筛选出来，最终效果就是得到一个这样顺序的一级数组
KKK
QQQ
JJJ
HHH
GGG
LLL
需要根据AAA这个节点和他所有子节点的数据，构造出一个无限级树型结构，如下
数据
顶级AAA数据
{"id":348019,"name":"AAA","is_leaf":2,"parent_id":347234,"type":0,"order":["348020"]}
AAA所有的孩子节点
[{"id":348020,"name":"BBB","is_leaf":2,"parent_id":348019,"type":0,"order":["348037","348033","348021","348023","348034"]},{"id":348021,"name":"CCC","is_leaf":2,"parent_id":348020,"type":0,"order":["348022","348035"]},{"id":348022,"name":"DDD","is_leaf":2,"parent_id":348021,"type":0,"order":["348024","348032","348030"]},{"id":348024,"name":"EEE","is_leaf":2,"parent_id":348022,"type":0,"order":["348025","348036"]},{"id":348025,"name":"FFF","is_leaf":2,"parent_id":348024,"type":0,"order":["348031"]},{"id":348030,"name":"HHH","is_leaf":1,"parent_id":348022,"type":11,"order":[]},{"id":348023,"name":"GGG","is_leaf":1,"parent_id":348020,"type":11,"order":[]},{"id":348031,"name":"QQQ","is_leaf":1,"parent_id":348025,"type":11,"order":[]},{"id":348032,"name":"JJJ","is_leaf":1,"parent_id":348022,"type":11,"order":[]},{"id":348035,"name":"MMMu65e0u53f6u5b50","is_leaf":2,"parent_id":348021,"type":0,"order":[]},{"id":348036,"name":"NNNu65e0u53f6u5b50","is_leaf":2,"parent_id":348024,"type":0,"order":[]},{"id":348033,"name":"KKK","is_leaf":1,"parent_id":348020,"type":11,"order":[]},{"id":348037,"name":"OOO","is_leaf":2,"parent_id":348020,"type":0,"order":[]},{"id":348034,"name":"LLL","is_leaf":1,"parent_id":348020,"type":11,"order":[]}]
节点数据库结构都一样，核心是有一个parent_id，每个节点会保存直属叶子的排序order
实现
其实这里考察的是递归思想构造无限级，还有如果遍历一棵树，话不多说，上套路
构造无限级
private function getTree($list, $node)
{
$tree = [];
foreach ($list as $k => $v) {
if ($v['parent_id'] == $node['id']) {
$v['children'] = $this->getTree($list, $v);
$tree[] = $v;
}
}
if (empty($node['order'])) {
return [];
}
//注意：为了保证所有的叶子节点是根据已有的order排序，这里我们重新摆放一下
$treeMap = [];
foreach ($tree as $v) {
$treeMap[$v['id']] = $v;//建立id和数据的map
}
//根据order重新排序
$orderTree = [];
foreach ($node['order'] as $id) {//根据order的顺序重新摆放
$orderTree[] = $treeMap[$id];
}
return $orderTree;
}
我们来使用一下，使用如下
最终输出的json如下
可以看到，已经构造出了一个无限级的树，并且和我们的界面是一模一样的层级和顺序
拉下来现在我们要遍历这棵树，为了获取到所有is_leaft=1的节点，我们先用广度优先遍历来试一下，因为这个对于找节点来说性能比较高
广度优先遍历
代码如下
private function bfsFindLeafs($node)
{
$result = [];//满足条件的组合
$q = [];
$q[] = $node;
while (count($q) > 0) {
$size = count($q);
for ($i = 0; $i < $size; $i++) {
$current = array_pop($q);
//判断节点如果是满足条件，加入路径
if ($current['is_leaf'] == 1) {
$result[] = $current;
}
//把所有的子节点加入队列
foreach ($current['children'] as $v) {
$q[] = $v;
}
}
}
return $result;
}
我们来使用一下
$getAllLeafs = $this->bfsFindLeafs($topNode);
echo json_encode($getAllLeafs);
运行后输出
[
{
"id": 348034,
"name": "LLL",
"is_leaf": 1,
"parent_id": 348020,
"type": 11,
"order": [],
"children": []
},
{
"id": 348023,
"name": "GGG",
"is_leaf": 1,
"parent_id": 348020,
"type": 11,
"order": [],
"children": []
},
{
"id": 348030,
"name": "HHH",
"is_leaf": 1,
"parent_id": 348022,
"type": 11,
"order": [],
"children": []
},
{
"id": 348032,
"name": "JJJ",
"is_leaf": 1,
"parent_id": 348022,
"type": 11,
"order": [],
"children": []
},
{
"id": 348031,
"name": "QQQ",
"is_leaf": 1,
"parent_id": 348025,
"type": 11,
"order": [],
"children": []
},
{
"id": 348033,
"name": "KKK",
"is_leaf": 1,
"parent_id": 348020,
"type": 11,
"order": [],
"children": []
}
]
好，我们已经可以获取到所有is_leaf为1的节点了，但是这里有一个问题，不是从上到下输出的
LLL
GGG
HHH
JJJ
QQQ
KKK
这时候，我们就需要一个深度优先遍历来实现了
深度优先遍历
深度优先遍历其实就是回滚算法的一种，为了从上到下输出，需要先序遍历
private function dfsFindLeafs($node)
{
$trackList = [];
foreach ($node['children'] as $v) {
if ($v['is_leaf'] == 1) {
$trackList[] = $v;
}
if (empty($v['children'])) {
continue;
}
$trackList = array_merge($trackList,$this->dfsFindLeafs($v));
}
return $trackList;
}
我们再来运行一下
$getAllLeafs = $this->dfsFindLeafs($topNode);
echo json_encode($getAllLeafs);
输出
[
{
"id": 348033,
"name": "KKK",
"is_leaf": 1,
"parent_id": 348020,
"type": 11,
"order": [],
"children": []
},
{
"id": 348031,
"name": "QQQ",
"is_leaf": 1,
"parent_id": 348025,
"type": 11,
"order": [],
"children": []
},
{
"id": 348032,
"name": "JJJ",
"is_leaf": 1,
"parent_id": 348022,
"type": 11,
"order": [],
"children": []
},
{
"id": 348030,
"name": "HHH",
"is_leaf": 1,
"parent_id": 348022,
"type": 11,
"order": [],
"children": []
},
{
"id": 348023,
"name": "GGG",
"is_leaf": 1,
"parent_id": 348020,
"type": 11,
"order": [],
"children": []
},
{
"id": 348034,
"name": "LLL",
"is_leaf": 1,
"parent_id": 348020,
"type": 11,
"order": [],
"children": []
}
]
顺序为
KKK
QQQ
JJJ
HHH
GGG
LLL
这次顺序终于对了，oh yeah~，和我们之前的界面垂直顺序一致
完整代码
下面给出完整代码
/**
* Class Test
* @author chenqionghe
*/
class Test
{
public function run()
{
$topNodeJson = '{"id":348019,"name":"AAA","is_leaf":2,"parent_id":347234,"type":0,"order":["348020"]}';
$childrenJson = '[{"id":348020,"name":"BBB","is_leaf":2,"parent_id":348019,"type":0,"order":["348037","348033","348021","348023","348034"]},{"id":348021,"name":"CCC","is_leaf":2,"parent_id":348020,"type":0,"order":["348022","348035"]},{"id":348022,"name":"DDD","is_leaf":2,"parent_id":348021,"type":0,"order":["348024","348032","348030"]},{"id":348024,"name":"EEE","is_leaf":2,"parent_id":348022,"type":0,"order":["348025","348036"]},{"id":348025,"name":"FFF","is_leaf":2,"parent_id":348024,"type":0,"order":["348031"]},{"id":348030,"name":"HHH","is_leaf":1,"parent_id":348022,"type":11,"order":[]},{"id":348023,"name":"GGG","is_leaf":1,"parent_id":348020,"type":11,"order":[]},{"id":348031,"name":"QQQ","is_leaf":1,"parent_id":348025,"type":11,"order":[]},{"id":348032,"name":"JJJ","is_leaf":1,"parent_id":348022,"type":11,"order":[]},{"id":348035,"name":"MMMu65e0u53f6u5b50","is_leaf":2,"parent_id":348021,"type":0,"order":[]},{"id":348036,"name":"NNNu65e0u53f6u5b50","is_leaf":2,"parent_id":348024,"type":0,"order":[]},{"id":348033,"name":"KKK","is_leaf":1,"parent_id":348020,"type":11,"order":[]},{"id":348037,"name":"OOO","is_leaf":2,"parent_id":348020,"type":0,"order":[]},{"id":348034,"name":"LLL","is_leaf":1,"parent_id":348020,"type":11,"order":[]}]';
$topNode = json_decode($topNodeJson, true);
$childrenList = json_decode($childrenJson, true);
$topNode['children'] = $this->getTree($childrenList, $topNode);
$getAllLeafs = $this->dfsFindLeafs($topNode);
echo json_encode($getAllLeafs);
}
/**
* 递归构造无限级树
*
* @param $list
* @param $node
* @return array
*/
private function getTree($list, $node)
{
$tree = [];
foreach ($list as $k => $v) {
if ($v['parent_id'] == $node['id']) {
$v['children'] = $this->getTree($list, $v);
$tree[] = $v;
}
}
if (empty($node['order'])) {
return [];
}
//注意：为了保证所有的叶子节点是根据已有的order排序，这里我们重新摆放一下
$treeMap = [];
foreach ($tree as $v) {
$treeMap[$v['id']] = $v;//建立id和数据的map
}
//根据order重新排序
$orderTree = [];
foreach ($node['order'] as $id) {//根据order的顺序重新摆放
$orderTree[] = $treeMap[$id];
}
return $orderTree;
}
/**
* 广度优先遍历获取所有叶子
* @param $node
* @return array
*/
private function bfsFindLeafs($node)
{
$result = [];//满足条件的组合
$q = [];
$q[] = $node;
while (count($q) > 0) {
$size = count($q);
for ($i = 0; $i < $size; $i++) {
$current = array_pop($q);
//判断节点如果是满足条件，加入路径
if ($current['is_leaf'] == 1) {
$result[] = $current;
}
//把所有的子节点加入队列
foreach ($current['children'] as $v) {
$q[] = $v;
}
}
}
return $result;
}
/**
* 获取所有的叶子路径(深度度优先遍历)
*/
private function dfsFindLeafs($node)
{
$trackList = [];
foreach ($node['children'] as $v) {
if ($v['is_leaf'] == 1) {
$trackList[] = $v;
}
if (empty($v['children'])) {
continue;
}
$trackList = array_merge($trackList, $this->dfsFindLeafs($v));
}
return $trackList;
}
}
(new Test())->run();
ok，到这里我们就已经学会如何构造无限级树型结构，并学会用深度优先遍历垂直输出指定条件节点，还知道了怎么用广度优先遍历，giao~
程序员灯塔
转载请注明原文链接：无限级树构造并遍历输出指定条件叶子
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