有点变化的经典广度优先

/*
// 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<vector<int>> levelOrder(Node* root) {
        vector<vector<int>>ans;
        vector<int>tmp;
        queue<Node *>q;
        
        if(!root) return ans;
        
        q.push(root);
        while(!q.empty())
        {
            queue<Node *>q1;
            tmp.clear();
            while(!q.empty())
            {
                tmp.push_back(q.front()->val);
                q1.push(q.front());
                q.pop();
            }
            ans.push_back(tmp);
            while(!q1.empty())
            {
                Node * t = q1.front();
                for(int i = 0;i<(t->children).size();i++)
                {
                    if(t->children[i])
                        q.push(t->children[i]);
                }
                q1.pop();
            }
        }
        return ans;
    }
};