Binary Tree Right Side View

/**
 * 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:
    void helper(TreeNode* root,vector<int>& ans){
        if(root==NULL)
            return;
        ans.push_back(root->val);
        
        if(root->right!=NULL)
            return helper(root->right,ans);
        else if(root->left!=NULL)
            return helper(root->left,ans);
        else
            return;
    }
    vector<int> rightSideView(TreeNode* root) {
        vector<int> ans;
        if(root==NULL)
            return ans;
        /*helper(root,ans);
        return ans;*/
        queue<TreeNode*> q;
        q.push(root);
        q.push(NULL);
        
        bool pushit=true;
        while(!q.empty()){
            TreeNode* temp=q.front();
            q.pop();
            if(temp==NULL){
                if(!q.empty())
                    q.push(NULL);
                pushit=true;
            }
            else{
                if(pushit)
                    ans.push_back(temp->val);
                if(temp->right)
                    q.push(temp->right);
                if(temp->left)
                    q.push(temp->left);
                /*while(q.front()!=NULL)
                    q.pop();*/
                pushit=false;
            }
        }
        return ans;
    }
};