Symmetric Tree

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isSymmetric(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(root==NULL)
        return true;
        vector<TreeNode *> left;
        vector<TreeNode *> right;
        vector<TreeNode *> templ;
        vector<TreeNode *> tempr;
        templ.push_back(root);
        tempr.push_back(root);
        while(!templ.empty()&&!tempr.empty())
        {
            vector<TreeNode*> prel;
            vector<TreeNode*> prer;
            int size = tempr.size();
            for(int i = 0;i < size;i++)
            {
                if(templ[i]->left != NULL)
                {
                    if(tempr[i]->right == NULL)
                    return false;
                    else if(tempr[i]->right->val == templ[i]->left->val)
                    {
                        prer.push_back(tempr[i]->right);
                        prel.push_back(templ[i]->left);
                    }
                    else
                    {
                        return false;
                    }
                }
                if(templ[i]->right != NULL)
                {
                    if(tempr[i]->left == NULL)
                    return false;
                    else if(templ[i]->right->val == tempr[i]->left->val)
                    {
                        prer.push_back(tempr[i]->left);
                        prel.push_back(templ[i]->right);
                    }
                    else
                    {
                        return false;
                    }
                }
            }
            templ = prel;
            tempr = prer;
        }
        return true;
    }
};