题解 | #牛群的重新排列#

设置虚拟头结点，虚拟头的next为head

pre跳left-1下来到操作节点前

cur指向pre.next即操作节点

然后开始逆转循环~~~

public class Solution {

    public ListNode reverseBetween (ListNode head, int left, int right) {
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        ListNode pre = dummy;

        for (int i = 1; i < left; i++) {
            pre = pre.next;
        }

        ListNode cur = pre.next;

        for (int i = left; i < right; i++) {
            ListNode tmp = cur.next;
            cur.next = tmp.next;
            tmp.next = pre.next;
            pre.next = tmp;
        }

        return dummy.next;
    }
}