LeetCode: Reverse Linked List II

Reverse a linked list from position m to n. Do it in-place and in one-pass.

For example:
Given 1->2->3->4->5->NULL, m = 2 and n = 4,

return 1->4->3->2->5->NULL.

Note:
Given m, n satisfy the following condition:
1 ≤ m ≤ n ≤ length of list.

Solution:
At first I misunderstood the problem. I thought it requires to exchange the mth and the nth node. The code is as follows

The real intention of this problem is to reverse all nodes between the mth and the nth node. Code: