Leetcode 429 N叉树的前序遍历

给定一个 N 叉树，返回其节点值的层序遍历。 (即从左到右，逐层遍历)。

例如，给定一个 3叉树 :

返回其层序遍历:

[
     [1],
     [3,2,4],
     [5,6]
]

说明:

1. 树的深度不会超过 1000。
2. 树的节点总数不会超过 5000。

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

    Node() {}

    Node(int _val, vector<Node*> _children) {
        val = _val;
        children = _children;
    }
};
*/

class Solution {
public:
    vector<vector<int>> levelOrder(Node* root) 
    {
        vector<vector<int>> res;
        if(root==NULL)
            return res;
        queue<Node*> q;
        q.push(root);
        Node* temp;
        int nowcount=1,nextcount=0;
        vector<int> lev;
        lev.push_back(root->val);
        res.push_back(lev);
        while(!q.empty())
        {
            vector<int> lev;
            while(nowcount>0)
            {
                temp = q.front();
                int n = temp->children.size();
                for(int i=0;i<n;i++)
                {
                     if(temp->children[i])
                     {
                         q.push(temp->children[i]);
                         lev.push_back(temp->children[i]->val);
                         nextcount++;
                     }
                }
             
                q.pop();
                nowcount--;
            }
            if(!lev.empty())
            {
                res.push_back(lev);
            }
            nowcount = nextcount;
            nextcount=0;
        }
        return res;
    }
    
};