Count Complete Tree Nodes

/**
* 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 traverseLeft(TreeNode* root, int& h)
{
if(root == NULL)
{
return;
}
++ h;
traverseLeft(root -> left, h);

}
void traverseRight(TreeNode* root, int& h)
{
if(root == NULL)
{
return;
}
++ h;
traverseRight(root -> right, h);
}

int countNodes(TreeNode* root)
{
if(root == NULL)
{
return 0;
}
int h1 = 1;
int h2 = 1;
traverseLeft(root -> left, h1);
traverseRight(root -> right, h2);
if(h1 == h2)
{
return pow(2, h1) - 1;
}
//int h = max(h1, h2);

return countNodes(root -> left) + countNodes(root -> right) + 1;

}
};