https://leetcode-cn.com/problems/n-ary-tree-postorder-traversal/submissions/
在构造数据上花费了功夫。
<?php class Node{ public $val = null; public $children = null; function __construct($val = 0){ $this->val = $val; $this->children = array(); } } class Solution { /** * @param Node $root * @return integer[] */ public function postorder($root) { $result = []; $this->getData($root, $result); //后续遍历，最后把根节点值放入 $result[] = $root->val; return $result; } /** * 递归遍历，终止条件为：root为空,其实就是children为空 */ public function getData($root,&$result){ if($root == null) return; foreach($root->children as $children) { //该地方一定要把children传递过去，很多人会传root，造成死循环 $this->getData($children,$result); $result[] = $children->val; } } } //构造数据一定要有想象空间，所谓的n叉树其实就是递归。 $a = new Node(); $a->val = 1; $e = new Node(); $e->val = 5; $f = new Node(); $f->val = 6; $b = new Node(); $b->val = 3; $b->children = [$e,$f]; $c = new Node(); $c->val = 2; $d = new Node(); $d->val = 4; $a->children = [$b,$c,$d]; $s = new Solution(); $s->postorder($a); ?>前序遍历
https://leetcode-cn.com/problems/n-ary-tree-preorder-traversal/submissions/
<?php class Node{ public $val = null; public $children = null; function __construct($val = 0){ $this->val = $val; $this->children = array(); } } class Solution { function preorder($root) { $result = []; $result[] = $root->val; $this->getPreData($root,$result); return $result; } function getPreData($root,&$result){ if($root == null) return; foreach($root->children as $children) { $result[] = $children->val; $this->getPreData($children,$result); } } } //构造数据一定要有想象空间，所谓的n叉树其实就是递归。 $a = new Node(); $a->val = 1; $e = new Node(); $e->val = 5; $f = new Node(); $f->val = 6; $b = new Node(); $b->val = 3; $b->children = [$e,$f]; $c = new Node(); $c->val = 2; $d = new Node(); $d->val = 4; $a->children = [$b,$c,$d]; $s = new Solution(); print_r($s->preorder($a)); ?>
