230. Kth Smallest Element in a BST

 230. Kth Smallest Element in a BST

Given the root of a binary search tree, and an integer k, return the kth smallest value (1-indexed) of all the values of the nodes in the tree.

Example 1:

Input: root = [3,1,4,null,2], k = 1
Output: 1

Example 2:

Input: root = [5,3,6,2,4,null,null,1], k = 3
Output: 3

Question link

Solution:

class Solution {
    vector<int>vt;
public:
    void inorder(TreeNode* root)
    {
        if(root==NULL)
            return;
        inorder(root->left);
        vt.push_back(root->val);
        inorder(root->right);
    }
    
    int kthSmallest(TreeNode* root, int k) {
        inorder(root);
        return vt[k-1];
        
    }
};