[Python3] Faster 98.65% Memory 99.79% || TC : O(N) || SC: O(1) MORRIS TRAVERSAL
\ndef kthSmallest(self, root: Optional[TreeNode], k: int) -> int:\n        \n        pos = 0\n        ans = 0\n        \n        current = root\n        \n     
```\ndef kthSmallest(self, root: Optional[TreeNode], k: int) -> int:\n        \n        pos = 0\n        ans = 0\n        \n        current = root\n        \n        while current and pos < k:\n            \n            if not current.left:\n                pos += 1\n                ans = current.val\n                current = current.right\n            \n            else:\n                pre = current.left\n                while pre.right:\n                    pre = pre.right\n                \n                pre.right = current\n                left = current.left\n                current.left = None\n                current = left\n        \n        return ans\n\n```
['Python3']