【leetcode】Binary Tree Level Order Traversal

/**
* Definition for binary tree
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:

vector<vector<int> > levelOrder(TreeNode *root) {
// Note: The Solution object is instantiated only once and is reused by each test case.
vector<vector<int> >ans;
if(root==NULL)
return ans;

vector<int> vec;//每一层的节点放入里面
queue<TreeNode *> que;
que.push(root);
int count=1;//上一层的在队列中的节点数
while(que.empty()==false)
{
vec.clear();
int nextCount=0;//接下来的下一层的节点数的统计
for(int i=0;i<count;i++)//弹出上一层的节点进行处理
{
TreeNode *curNode=que.front();
que.pop();

vec.push_back(curNode->val);//

if(curNode->left!=NULL)
{
que.push(curNode->left);
nextCount++;
}
if(curNode->right!=NULL)
{
que.push(curNode->right);
nextCount++;
}
}
count=nextCount;
ans.push_back(vec);
}
return ans;
}
};