Reverse Linked List II (problem from LeetCode)

Objective: Write a function reverseBetween to reverse a singly linked list from position m to n. Do it in one-pass.

• Note: 1 ≤ m ≤ n ≤ length of list.

  Example:

  Input: 1 -> 2 -> 3 -> 4 -> 5 -> NULL, m = 2, n = 4
  Output: 1 -> 4 -> 3 -> 2 -> 5 -> NULL
  

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Source: 92. Reverse Linked List II