solve: kthSmallestElementInABst

Author: yolophg

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

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+# Time Complexity: O(N) - visit each node once in an inorder traversal.
+# Space Complexity: O(N) - store all node values in a list.
+
+class Solution:
+    def kthSmallest(self, root: Optional[TreeNode], k: int) -> int:
+        def inorder(node):
+            if not node:
+                return
+            
+            # go left (smaller values first)
+            inorder(node.left) 
+            # add the current node's value
+            values.append(node.val)  
+            # go right (larger values next)
+            inorder(node.right) 
+
+        values = []
+        inorder(root)
+        
+        # get the k-th smallest element (1-based index)
+        return values[k - 1]