429. N-ary Tree Level Order Traversal | Leetcode solution

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 429. N-ary Tree Level Order Traversal

Given an n-ary tree, return the level order traversal of its nodes' values.

Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).

 

Example 1:

Input: root = [1,null,3,2,4,null,5,6]
Output: [[1],[3,2,4],[5,6]]

Example 2:

Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: [[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]

 

Constraints:

  • The height of the n-ary tree is less than or equal to 1000
  • The total number of nodes is between [0, 104]



solution:

/*
// 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<vector<int>> levelOrder(Node* root) {
        
        vector<vector<int>>result;
        queue<Node*>q1;
        queue<Node*>q2;
        q1.push(root);
        if(root == NULL)
        {   
            return result;
        }
        result.push_back({q1.front()->val});
        int i = 0;
        while(true)
        {
            vector<int>j;
        while(!q1.empty())
        {
            Node *temp = q1.front();
            vector<Node*>vect = temp->children;
            int s = vect.size();
            for(int l =0 ; l < s ; l++)
            {
                if(vect[l] != NULL)
                {
                    q2.push(vect[l]);
                    j.push_back(vect[l]->val);
                }

            }
            
            q1.pop();
            

        }   
            result.push_back(j);
            if(q2.empty())
                break;
            q1 = q2;
            while(!q2.empty())
            {
                  q2.pop();
            }
            i++;
        }
        result.pop_back();
        
      return result;
    }
};




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