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:
    vector<int> rightSideView(TreeNode* root) {
        vector<int> res;
        TreeNode * temp=root;
        while(temp!=NULL)
        {
            res.push(temp->val)
            if(temp->right!=NULL)
                temp=temp->right;
            else
                temp=temp->left;
        }
        return res;
    }
};