【牛客题霸题解】二叉树的层序遍历（待更新）

/**
 * struct TreeNode {
 *    int val;
 *    struct TreeNode *left;
 *    struct TreeNode *right;
 * };
 */
struct node{
    int index;
    TreeNode *root;
};
#include<queue>
class Solution {
public:
    /**
     * @param root TreeNode类 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > levelOrder(TreeNode* root) {
        // write code here
        vector<vector<int> > t;
        if(root==NULL)return t;
        queue <node>  Q;
        vector<node>  save;
        Q.push(node{0,root});
        while(!Q.empty())
        {
            node top=Q.front();
            Q.pop();
            save.push_back(top);
            if(top.root->left != NULL){Q.push(node{top.index+1,top.root->left});}
            if(top.root->right != NULL){Q.push(node{top.index+1,top.root->right});}
        }
       int num = save.size();
      // cout<<num;
       vector<vector<int> > ans(save[num-1].index+1);
       for(int i = 0 ; i < num ; i++)
       {
           ans[save[i].index].push_back(save[i].root->val);
       }
        return ans;
    }
};