I’m working on implementing a Binary Search Tree (BST) in Python and I’m running into an issue when the tree encounters duplicate values. I understand that traditionally, a BST doesn’t handle duplicates, but I want to modify my tree to allow duplicate values either by storing them in the left subtree, right subtree, or using some other strategy.
class TreeNode:
def __init__(self, key):
self.left = None
self.right = None
self.value = key
def insert(root, key):
if root is None:
return TreeNode(key)
else:
if root.value < key:
root.right = insert(root.right, key)
elif root.value > key:
root.left = insert(root.left, key)
else:
# Attempt to handle duplicates (not working correctly)
root.right = insert(root.right, key)
return root
When I try to insert duplicate values, it seems that the tree is not maintaining its structure properly, and my search operations don’t return the expected results.What is the best strategy to handle duplicate values in a Binary Search Tree? What changes should I make to my insertion function to correctly handle duplicates? Are there any potential pitfalls with this approach that I should be aware of?
Ashi Thilakarathna is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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4
Allow Duplicates in the Left or Right Subtree:
Left Subtree: If the node’s value is equal to the key, you can insert the duplicate value into the left subtree.
Right Subtree: Alternatively, you could insert the duplicate value into the right subtree.
def insert(root, key):
if root is None:
return TreeNode(key)
else:
if root.value < key:
root.right = insert(root.right, key)
else:
root.left = insert(root.left, key)
return root
Note: By inserting duplicates into the left subtree, you maintain the property where all left descendants are less than or equal to the node’s value.
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