把二叉树打印成多行

题目描述

从上到下按层打印二叉树，同一层结点从左至右输出。每一层输出一行。

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
        vector<vector<int> > Print(TreeNode* pRoot) {
            if(!pRoot) return {};
            vector<vector<int>> vvi;
            int level=0;
            queue<TreeNode*> q;
            q.push(pRoot);
            while(!q.empty())
                {
                ++level;
                int len=q.size();
                vector<int> vi;
                while(len--)
                    {
                    TreeNode* tem=q.front();
                    q.pop();
                    vi.push_back(tem->val);
                    if(tem->left) q.push(tem->left);
                    if(tem->right) q.push(tem->right);
                }
                vvi.push_back(vi);
            }
            return vvi;
        }
    
};