层序遍历二叉树

 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> > res;
15             vector<int> temp_vec;
16             queue<TreeNode*> q;
17             if(pRoot==nullptr) return res;
18             q.push(pRoot);
19             while(!q.empty()){
20                 int len=q.size();
21                 temp_vec.clear();
22                 //只存每一层的queue
23                 while(len--){
24                     TreeNode* tmp=q.front();
25                     temp_vec.push_back(tmp->val);
26                     q.pop();
27                     if(tmp->left) q.push(tmp->left);
28                     if(tmp->right) q.push(tmp->right);
29                 }
30                 res.push_back(temp_vec);
31             }
32             return res;
33         }
34     
35 };