kth smallest element in a BST

class Solution {
public:
  // first method
   int kthSmallest(TreeNode* root, int k) {
      int count = countNodes(root->left);
      if (k <= count) {
          return kthSmallest(root->left, k);
          }
      else
          if (k > count + 1) {
            return kthSmallest(root->right, k-1-count);
            }
      return root->val;
      }

  int countNodes(TreeNode* Node) {
      if (Node == NULL)
        return 0;
      return 1 + countNodes(Node->left) + countNodes(Node->right);
      }

  // second method
   /*
   int kthSmallest(TreeNode* root, int k) {
      stack<TreeNode *> s;
      queue<int>q;
      int res;
      TreeNode *curr = root;
      while (curr != NULL || s.empty() == false)  {
         while (curr !=  NULL) {
            s.push(curr);
            curr = curr->left;
            }
         curr = s.top();
         s.pop();
         q.push(curr->val );
         curr = curr->right;
         }
     while(k>0){
       res=q.front();
       q.pop();
       k--;
       }
    return res;
    }
    */
};