solve : solve kth smallest element in a bst

Author: SamTheKorean

kth-smallest-element-in-a-bst/samthekorean.py

@@ -0,0 +1,21 @@
+# TC : O(n)
+# SC : O(n)
+class Solution:
+    def kthSmallest(self, root: Optional[TreeNode], k: int) -> int:
+        n = 0
+        stack = []
+        cur = root
+
+        while cur or stack:
+            while cur:
+                stack.append(cur)
+                cur = cur.left
+
+            cur = stack.pop()
+            n += 1
+            if n == k:
+                return cur.val
+
+            cur = cur.right
+
+        return -1