LeetCode - Binary Tree Level Order Traversal

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]]

/** * 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<vector<int> > result;if(root==NULL){return result;}vector<int> levelVec;queue<pair<TreeNode*,int> > levelQueue;pair<TreeNode*,int>* tmp;int currLevel=0;levelQueue.push(make_pair(root,currLevel));while(!levelQueue.empty()){tmp=&levelQueue.front();levelQueue.pop();if(tmp->second!=currLevel){currLevel=tmp->second;result.push_back(levelVec);levelVec.clear();}levelVec.push_back(tmp->first->val);if(tmp->first->left){levelQueue.push(make_pair(tmp->first->left,tmp->second+1));}if(tmp->first->right){levelQueue.push(make_pair(tmp->first->right,tmp->second+1));}}result.push_back(levelVec);        return result;    }};