Convert Sorted List to BST

convert_list_to_bst.py

class Solution:
    def sortedListToBST(self, head: ListNode) -> TreeNode:
        curr, count = head, 0
        while curr:
            curr = curr.next
            count += 1
        def treeify(i: int, j: int) -> TreeNode:
            if j < i: return None
            mid, node = i + j >> 1, TreeNode()
            node.left = treeify(i, mid - 1)
            node.val, curr[0] = curr[0].val, curr[0].next
            node.right = treeify(mid + 1, j)
            return node
        curr = [head]
        return treeify(1, count)