Difficulty: Medium
Reverse a 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
Language: Java
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode reverseBetween(ListNode head, int m, int n) {
ListNode fakeNode = new ListNode(-1);
fakeNode.next = head;
ListNode p = fakeNode;
ListNode q = head;
int index = 1;
while (q.next != null) {
if (index >= m && index < n) {
ListNode node = q.next;
q.next = q.next.next;
node.next = p.next;
p.next = node;
} else {
q = q.next;
}
if (index < m) {
p = p.next;
}
if (++index >= n) {
break;
}
}
return fakeNode.next;
}
}