Create bst_delete_node.py

trees/bst_delete_node.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
+
+def successor(root):
+   
+    root = root.right
+    while root.left:
+            root = root.left
+    return root.val
+
+
+def predecessor(root):
+  
+    root = root.left
+    while root.right:
+            root = root.right
+    return root.val
+
+
+def delete_node(root, key):
+        
+    if not root:
+            return root
+
+    if key > root.val:
+            root.right = deleteNode(root.right, key)
+      
+    elif key < root.val:
+            root.left = deleteNode(root.left, key)
+      
+    else:
+        if not (root.left or root.right):
+            root = None
+          
+        elif root.right:
+            root.val = successor(root)
+            root.right = deleteNode(root.right, root.val)
+          
+        else:
+            root.val = predecessor(root)
+            root.left = deleteNode(root.left, root.val)
+        
+    return root
+