"Kth smallest Element in a BST" CPP

Topic:

Given A binary search tree, write a function to kthSmallest find the kth smallest element in it.

Note:
You may assume k are always valid, 1≤k≤bst's total elements.

Follow up:
What if the BST are modified (Insert/delete operations) often and you need to find the kth smallest frequently? How would optimize the Kthsmallest routine?

Hint:

1. Try to utilize the property of a BST.
2. What if you could modify the BST node ' s structure?
3. The optimal runtime complexity is O (height of BST).

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

Code:

/** Definition for a binary tree node. * struct TreeNode {* int val; * TreeNode *left; * TreeNode *right; * TreeNode (int x): Val (x), left (null), right (NULL) {} *}; */classSolution { Public:    intKthsmallest (treenode* root,intk) {intCount =0; Stack<TreeNode*>STA; TreeNode* Curr =Root;  while(!sta.empty () | |Curr) {                if(Curr) {Sta.push (Curr); Curr= curr->Left ; }                Else{Curr=Sta.top ();                    Sta.pop (); Count++; if(count==k)returnCurr->Val; Curr= curr->Right ; }            }            returnCurr->Val; }};

Tips

The intuitive approach is to traverse BST in the middle sequence and then get the K element.

"Kth smallest Element in a BST" CPP