力扣-589题 N叉树的前序遍历（C++）- N叉树迭代前序遍历

朱雀 2022-09-02 03:59 153阅读 0赞

题目链接：[https://leetcode-cn.com/problems/n-ary-tree-preorder-traversal/][https_leetcode-cn.com_problems_n-ary-tree-preorder-traversal]  
题目如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwNDY3Njcw_size_16_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwNDY3Njcw_size_16_color_FFFFFF_t_70 1]

/*
    // Definition for a Node.
    class Node {
    public:
        int val;
        vector<Node*> children;
    
        Node() {}
    
        Node(int _val) {
            val = _val;
        }
    
        Node(int _val, vector<Node*> _children) {
            val = _val;
            children = _children;
        }
    };
    */
    
    class Solution {
        
    public:
        vector<int> preorder(Node* root) {
        
            vector<int> result;
            if(root==NULL) return result;
    
            stack<Node*> stk;
            stk.push(root);
    
            while(!stk.empty()){
        
                Node* node=stk.top();
                stk.pop();
    
                if(node!=NULL) result.push_back(node->val);
    
                for(int i=node->children.size()-1;i>=0;i--){
        
                    Node* temp=node->children[i];
                    if(temp!=NULL) stk.push(temp);
                }
            }
    
            return result;       
        }
    };

[https_leetcode-cn.com_problems_n-ary-tree-preorder-traversal]: https://leetcode-cn.com/problems/n-ary-tree-preorder-traversal/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwNDY3Njcw_size_16_color_FFFFFF_t_70]: /images/20220829/ebbd1981159d4e5dbfdde25b26f888df.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwNDY3Njcw_size_16_color_FFFFFF_t_70 1]: /images/20220829/414bbee2100443689761b011b71808a6.png