构造无限级树并深度遍历查找指定节点

目录

• 前言
• 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

前言

最近接到一个关于树的需求，想起了大学那会儿听过俞敏洪有关树的演讲，老师重复在课上放了很多次，N年过去了印象还是很深。
演讲内容是介样的，让我们一起来喝汤~

人的生活方式有两种，
第一种方式是像草一样活着，
你尽管活着，
每年还在成长，
但是你毕竟是一棵草，
你吸收雨露阳光，
但是却长不大。
人们可以踩过你，
但是人们不会因为你的痛苦，而他产生痛苦；
人们不会因为你被踩了，而来怜悯你，
因为人们本身就没有看到你。
所以我们每一个人，
都应该像树一样的成长，
即使我们现在什么都不是，
但是只要你有树的种子，
即使你被踩到泥土中间，
你依然能够吸收泥土的养分，
自己成长起来。
当你长成参天大树以后，
遥远的地方，人们就能看到你；
走近你，你能给人一片绿色。
活着是美丽的风景，
死了依然是栋梁之才，
活着死了都有用。

需求是这样的：
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

其实这里考察的递归构造树、广度优先遍历、深度优先遍历
其实不管啥语言，思想都是这样，因为这个需求是php写的接口，就用php给出实现代码，气氛搞起来~

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

$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, $topNode);
echo json_encode($topNode);

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($node)
    {
        if (empty($node['children'])) {
            return [];
        }
        $result = [];//满足条件的组合
        $q = [];
        $q[] = $node['children'][0];
        while (count($q) > 0) {
            $size = count($q);
            for ($i = 0; $i < $size; $i++) {
                $current = array_shift($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": 348033,
        "name": "KKK",
        "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": 348034,
        "name": "LLL",
        "is_leaf": 1,
        "parent_id": 348020,
        "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": 348031,
        "name": "QQQ",
        "is_leaf": 1,
        "parent_id": 348025,
        "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，是最近输出的

KKK->GGG->LLL->JJJ->HHH->QQQ

其实这就是因为广度优先遍历是最近输出的，为了从上到下输出，我们需要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溯算法的一种，为了从上到下输出，需要先序遍历

    /**
     * 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;
    }

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

<?php

/**
 * 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)
    {
        if (empty($node['children'])) {
            return [];
        }
        $result = [];//满足条件的组合
        $q = [];
        $q[] = $node['children'][0];
        while (count($q) > 0) {
            $size = count($q);
            for ($i = 0; $i < $size; $i++) {
                $current = array_shift($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~