N-叉树--后序遍历

590. N-ary Tree Postorder Traversal

Easy

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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]​​.

/*
// Definition for a Node.
class Node {
public:
    int val;
    vector<Node*> children;

    Node() {}

    Node(int _val, vector<Node*> _children) {
        val = _val;
        children = _children;
    }
};
*/
class Solution {
public:
    void postorder(vector<int>& Res,Node* root){
        s.push(root);
        while(!s.empty()){
            Node* tmp = s.top();
            s.pop();
            for(auto child : tmp->children){
                s.push(child);
            }
            Res.push_back(tmp->val);
        }
        reverse(Res.begin(),Res.end());
    }
    vector<int> postorder(Node* root) {
        vector<int> Res;
        if(root == NULL){return Res;}
        postorder(Res,root);
        return Res;
    }
private:
    vector<int> Result;
    stack<Node*> s;
};