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Binary Tree Level Order Traversal

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Given a binary tree, return the level order traversal of its nodes‘ values. (ie, from left to right, level by level).

For example:
Given binary tree {3,9,20,#,#,15,7},

    3
   /   9  20
    /     15   7

return its level order traversal as:

[
  [3],
  [9,20],
  [15,7]
]

confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.


/**
 * 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) {
        
        vector<int> vectorTemp;
        vector<vector<int> > vectorTotal;
        if(root==NULL)return vectorTotal;
        queue<TreeNode*> Q;
        TreeNode* p=root;
        Q.push(p);
        int counter=1;
        while(!Q.empty())
        {

            p=Q.front();
            Q.pop();
            counter--;

            vectorTemp.push_back(p->val);

            if(p->left!=NULL)Q.push(p->left);
            if(p->right!=NULL)Q.push(p->right);
            if(counter==0)
            {
                //vector<int> vectorTemp;
                vectorTotal.push_back(vectorTemp);
                vectorTemp.clear();
				counter=Q.size();
            }
        }
        //vectorTotal.push_back(vectorTemp);
        return vectorTotal;
    }
};