LeetCode 102. Binary Tree Level Order Traversal

练手水题，直接贴代码。快转正面试了，虚啊，鬼晓得BOSS会问点什么。

/**
 * Definition for a binary tree node.
 * 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>> results;
        if(root == NULL)
            return results;
        queue<TreeNode*>* currQueue = new queue<TreeNode*>();
        queue<TreeNode*>* candidateQueue = new queue<TreeNode*>();
        currQueue->push(root);
        vector<int> levelResult;
        while(!currQueue->empty()){
            TreeNode* currNode = currQueue->front();
            currQueue->pop();
            levelResult.push_back(currNode->val);
            if(currNode->left != NULL)
                candidateQueue->push(currNode->left);
            if(currNode->right != NULL)
                candidateQueue->push(currNode->right);
            if(currQueue->empty()){
                //swap curr and candidte
                results.push_back(levelResult);
                levelResult.clear();
                queue<TreeNode*>* temp = currQueue;
                currQueue = candidateQueue;
                candidateQueue = temp;
            }
        }
        return results;
    }
};