109.Convert Sorted List to Binary Search Tree Leetcode Python

Convert Sorted List to Binary Search Tree total accepted:32343 total submissions:117376 My submissions Question Solution

Given a singly linked list where elements is sorted in ascending order, convert it to a height balanced BST

The question and convert array to binary search tree differ in that there is no random access with LinkedList so to find the midpoint you can only use fast and slow pointer to find.

This method is slower than turning the LinkedList directly into an array.

The code is as follows:

# Definition for a  binary tree node# class treenode:#     def __init__ (self, x): #         self.val = x#         self.left = No ne#         self.right = none## Definition for singly-linked list.# class listnode:#     def __init__ (self, x): #         Self.val = x#         self.next = Noneclass solution:    # @param head, a list node    # @return A tree node    def conver T (self,head,tail):        if Head==tail:            return None        if Head.next==tail:            return TreeNode (head.val)        mid=head        Fast=head while        fast!=tail and Fast.next!=tail:            fast=fast.next.next            mid= Mid.next        Node=treenode (mid.val)        Node.left=self.convert (head,mid)        Node.right=self.convert ( Mid.next,tail)        return node    def sortedlisttobst (self, head):        return Self.convert (Head,none)        

109.Convert Sorted List to Binary Search Tree leetcode Python