92. 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.

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {    public ListNode reverseBetween(ListNode head, int m, int n) {        ListNode dummy = new ListNode(-1);        dummy.next = head;        ListNode cur = dummy;        for (int i = 1; i < m; i++) {            cur = cur.next;        }        ListNode pre = cur, last = cur.next, front = null;        for (int i = m; i <= n; i++) {            cur = pre.next;            pre.next = cur.next;            cur.next = front;            front = cur;        }        cur = pre.next;        pre.next = front;        last.next = cur;        return dummy.next;    }}