面试题61 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。

 1 /*
 2 struct TreeNode {
 3     int val;
 4     struct TreeNode *left;
 5     struct TreeNode *right;
 6     TreeNode(int x) :
 7             val(x), left(NULL), right(NULL) {
 8     }
 9 };
10 */
11 class Solution {
12 public:
13     vector<vector<int> > Print(TreeNode* pRoot) {
14         vector<vector<int> > vec;
15         if(pRoot == NULL) return vec;
16 
17         queue<TreeNode*> q;
18         q.push(pRoot);
19 
20         while(!q.empty())
21         {
22             int lo = 0, hi = q.size();
23             vector<int> c;
24             while(lo++ < hi)
25             {
26                 TreeNode *t = q.front();
27                 q.pop();
28                 c.push_back(t->val);
29                 if(t->left) q.push(t->left);
30                 if(t->right) q.push(t->right);
31             }
32             vec.push_back(c);
33         }
34         return vec;
35     }
36 };