I am trying to implement a binary search tree in python, but I can't find a solution for delete. If the item is in a leaf, that is simple, but what if the item I want to delete has 2 children which also have other children and so on ? How can in find its successor, so that I can replace it ? Are there any simple recursive solutions ?
class Node:
def __init__(self, data=None, left=None, right=None):
self.data = data
self.left = left
self.right = right
class BinarySearchTree:
def __init__(self, root=None):
self.root = Node(root)
def add(self, data, node):
if node == None:
node = Node(data)
return True
if data < node.data:
if node.left == None:
node.left = Node(data)
return True
else:
self.add(data, node.left)
elif data > node.data:
if node.right == None:
node.right = Node(data)
return True
else:
self.add(data, node.right)
def preorder(self, node):
if node != None:
print(node.data)
self.preorder(node.left)
self.preorder(node.right)
def inorder(self, node):
if node != None:
self.inorder(node.left)
print(node.data)
self.inorder(node.right)
def postorder(self, node):
if node != None:
self.postorder(node.left)
self.postorder(node.right)
print(node.data)
def retreive(self,item):
node = self.root
while node != None:
if node.data == item:
break
elif item < node.data:
if node.left != None:
if node.left.data == item:
node.left = None
return True
node = node.left
else:
if node.right != None:
if node.right.data == item:
node.right= None
return True
node = node.right
if node == None:
return False
tree = BinarySearchTree()
root=Node(3)
tree.add(55,root)
tree.add(5,root)
tree.add(13,root)
tree.add(2,root)
tree.add(3,root)
tree.preorder(root)
tree.postorder(root)
tree.inorder(root)
Also if you have any suggestions for what I've written so far, I'd really appreciate it. Thanks in advance.
If this isn't homework, you might use one of these:
Both implement deletion. Both deal well with sorted or unsorted inputs.
The red-black tree module has a BinaryTree class that RedBlackTree inherits from.
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