leetcode 450. Delete Node in a BST

Author: Partho Biswas

algoexpert.io/python/BST_Construction_Iterative.py

@@ -47,7 +47,7 @@ def remove(self, value, parentNode=None):
                 parentNode = currentNode
                 currentNode = currentNode.left
             elif value > currentNode.value:
-                parentNode = currentNode
+                paretNode = currentNode
                 currentNode = currentNode.right
             else:
                 if currentNode.left is not None and currentNode.right is not None:

leetcode.com/python/#450 - Delete Node in a BST.py

@@ -1,3 +1,5 @@
+# https://leetcode.com/problems/delete-node-in-a-bst/solution/
+
 # Definition for a binary tree node.
 # class TreeNode(object):
 #     def __init__(self, x):
@@ -6,9 +8,42 @@
 #         self.right = None
 
 class Solution(object):
+
+    def successor(self, root):
+        root = root.right
+        while root.left:
+            root = root.left
+        return root.val
+
+    def predecessor(self, root):
+        root = root.left
+        while root.right:
+            root = root.right
+        return root.val
+
     def deleteNode(self, root, key):
         """
         :type root: TreeNode
         :type key: int
         :rtype: TreeNode
         """
+        if root is None:
+            return None
+        if key < root.val:
+            root.left = self.deleteNode(root.left, key)
+        elif key > root.val:
+            root.right = self.deleteNode(root.right, key)
+        else:
+            if root.left is None and root.right is None:
+                root = None
+            elif root.right is not None:
+                succrssor = self.successor(root)
+                root.val = succrssor
+                root.right = self.deleteNode(root.right, succrssor)
+            elif root.left is not None:
+                predecessor = self.predecessor(root)
+                root.val = predecessor
+                root.left = self.deleteNode(root.left, predecessor)
+        return root
+
+