把二叉树打印成多行

牛客网题目

https://www.nowcoder.com/practice/445c44d982d04483b04a54f298796288?tpId=13&tqId=11213&tPage=3&rp=3&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

题目描述

从上到下按层打印二叉树，同一层节点从左至右输出，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) {
            vector<vector<int> > ans;
            if(pRoot == nullptr)
                return ans;
            queue<TreeNode*> q;
            q.push(pRoot);
            while(!q.empty()){
                vector<int> temp;
                for(int i = 0, n = q.size(); i < n; i++){
                    TreeNode* curNode = q.front();
                    q.pop();
                    temp.push_back(curNode->val);
                    if(curNode->left)
                        q.push(curNode->left);
                    if(curNode->right)
                        q.push(curNode->right);
                }
                ans.push_back(temp);
            }
            return ans;
        }
    
};