题解 | #二叉搜索树的第k个节点#

// 中序遍历
class Solution {
  public:
  public:
    int KthNode(TreeNode* proot, int k) {
        if (proot == nullptr) return -1;
        if (k == 0) return -1;
        std::vector<int> vec;
        Inorder(proot, vec);
        if (vec.size() >= k) {
            return vec[k - 1];
        } else
            return -1;
    }

  private:
    void Inorder(TreeNode* root, std::vector<int>& inputVec) {
        // 中序遍历
        if (root->left != nullptr) {
            Inorder(root->left, inputVec);
        }
        inputVec.push_back(root->val);
        if (root->right != nullptr) {
            Inorder(root->right, inputVec);
        }
    }

};