LeetCode 559 N叉树的最大深度

/*
// 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:
    int maxDepth(Node* root) {
        while(!root){
            return 0;
        }
        queue<Node *>q;
        q.push(root);
        int len,q_len;
        int depth=0;
        Node *p;
        while(!q.empty()){
            
            len=q.size();
            
            depth+=1;

            for(int i=0;i<len;++i){
               
                 p=q.front();
                 q.pop();
                
                 q_len=p->children.size();
                 
                 for(int j=0;j<q_len;++j){
                
                     q.push(p->children[j]);
                 }
            }
        }
        return depth;
    }
};