LeetCode_Binary Tree Level Order Traversal II

A过了，但是是那种BT解法，明天再想个正解

/**

 * 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> > levelOrderBottom(TreeNode *root) {

        // Start typing your C/C++ solution below

        // DO NOT write int main() function

        vector<vector<int>> result, result1;

        vector<int> tempR;

        queue<TreeNode *> a,b,c;

        if(root == NULL) return result;

        TreeNode *current;

        a.push(root);

        while(!a.empty()){

           

           tempR.clear();

           while(!a.empty())

           {

                current = a.front();

                a.pop();

                tempR.push_back(current->val);

                if(current->left)

                      b.push(current->left);

                if(current->right)

                      b.push(current->right);

           }

           result.push_back(tempR);

           c = a;

           a = b;

           b = c;

        }        

        

        for(int i =result.size()-1;i>=0;i--)

            result1.push_back(result[i]);

        return result1;

    }

};