leetcode-92 Reverse Linked List II

class Solution:
    def reverseBetween(self, head: Optional[ListNode], left: int, right: int) -> Optional[ListNode]:
        dummy_head = ListNode(-1, head)
        pre = dummy_head

        for _ in range(left - 1):
            pre = pre.next

        cur = pre.next
        for _ in range(right - left):
            next_node = cur.next
            cur.next = next_node.next
            next_node.next = pre.next
            pre.next = next_node

        return dummy_head.next