CODEWITHSUNDEEP
python-3.xbinary-search-tree
THE_GO_ODFATHER
THE_GO_ODFATHER

Reputation: 53

My BST function to find maximum element of left subtree and minimum element of right subtree wont return values

This is my function to return maximum element of left subtree and minimum element of right subtree

def Max(root):#this will return maximum element of left subtree
    if  root.left and not root.right:
        return root.data
    if root.right:
        Max(root.right)
    else:
        Max(root.left)
def Min(root):#this will return minimum element of right subtree
    if not root.left and not root.right:
        return root.data
    if root.left:
        Min(root.left)
    else:
        Min(root.right)
def InorderPreSuc(root):
    pre=Max(root.left)
    suc=Min(root.right)
    print(' predecessor {} and successor {}.format(pre,suc))

But my function wont return the values Why?

Upvotes: 1

Views: 512

Answers (1)

Shafi
Shafi

Reputation: 111

Maximum of left subtree would be finding the max at root.left, similarly minimum of right subtree would be the min of root.right

To recursively find min or max:

# Max of a BST would be its rightmost element
def Max(root):
    if root.right is not None:
        Max(root.right)
    return root.data

# Min of BST would be its leftmost element
def Min(root):
    if root.left is not None:
        Min(root.left)
    return root.data

Now to find maximum of left subtree call Max(root.left). We can add another check for null value in case the root is null.

def Min(root):
    if root is None:
        return float("-inf")
    if root.left is not None:
        Min(root.left)
    return root.data

Upvotes: 2

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