590. N-ary Tree Postorder Traversal

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#N-ary Tree #Postorder Traversal #590. N-ary Tree Postorder Trav

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本文介绍了一种不使用递归的迭代方法来实现N叉树的后序遍历，通过栈结构保存节点并逆序输出结果，提供了一个高效且易于理解的算法实现。

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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].

Note:

Recursive solution is trivial, could you do it iteratively?

/*
// 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> result;
      stack<Node*> stackNode;
     if(root == nullptr)
            return result;  
      stackNode.push(root);
      while(!stackNode.empty())
      {                            
          Node* temp = stackNode.top();
          stackNode.pop();
          result.push_back(temp->val);
          for(int i = 0 ; i < temp->children.size(); i++)
          {
            stackNode.push(temp->children[i]);
          }
      }
      reverse(result.begin(), result.end());
      return result;
    }
};