# 590. N-ary Tree Postorder Traversal

Given an n-ary tree, return the  postorder  traversal of its nodes’ values.

For example, given a `3-ary` tree:

Return its postorder traversal as: `[5,6,3,2,4,1]`.

Note:

Recursive solution is trivial, could you do it iteratively?

``````class Solution {
public:
vector<int> postorder(Node* root) {
vector<int> res;
helper(root, res);
return res;
}
void helper(Node* node, vector<int>& res) {
if (!node) return;
for (Node* child : node->children) {
helper(child, res);
}
res.push_back(node->val);
}
};
``````

``````class Solution {
public:
vector<int> postorder(Node* root) {
if (!root) return {};
vector<int> res;
stack<Node*> st{{root}};
while (!st.empty()) {
Node *t = st.top(); st.pop();
res.insert(res.begin(), t->val);
for (Node* child : t->children) {
if (child) st.push(child);
}
}
return res;
}
};
``````

Binary Tree Postorder Traversal

N-ary Tree Preorder Traversal

N-ary Tree Level Order Traversal

https://leetcode.com/problems/n-ary-tree-preorder-traversal/

https://leetcode.com/problems/n-ary-tree-postorder-traversal/discuss/147959/Java-Iterative-and-Recursive-Solutions

LeetCode All in One 题目讲解汇总(持续更新中…)

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