import java.util.*; class ListNode { int val; ListNode next = null; public ListNode(int val) { this.val = val; } } public class Solution { public ListNode reverseBetween(ListNode head, int m, int n) { ListNode dummy = new ListNode(-1); dummy.next = head; ListNode pre = dummy; // 找到反转部分的前一个节点 for (in...