LeetCode_590_N叉樹的後序周遊

題目描述：

算法思想：同二叉樹的後序周遊類似

/*
// 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:
    vector<int> res;
    vector<int> postorder(Node* root) {
        if(!root)
            return res;
        for(Node* child:root->children){
            postorder(child);
        }
        res.push_back(root->val);
        return res;
    }
};      

/*
// 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:
    vector<int> postorder(Node* root) {
        vector<int> res;
        stack<Node*> s;
        if(root==NULL)
            return res;
        s.push(root);
        while(!s.empty()){//讓棧中始終隻存在一層節點
            Node* now=s.top();
            s.pop();
            for(int i=0;i<now->children.size();i++){
                s.push(now->children[i]);
            }
            res.push_back(now->val);
        }
        reverse(res.begin(),res.end());
        return res;
    }
};