static void Main11(string[] args)
{
ListNode node1 = new ListNode(1);
ListNode node2 = new ListNode(2);
ListNode node3 = new ListNode(3);
node1.next = node2;
node2.next = node3;
ReverseBetween(node1,3,3);
}
//使用递归打印，跟使用栈一样
public static void PrintListReversingly_Recursively(ListNode head)
{
if (head == null)
return;
if (head != null)
{
PrintListReversingly_Recursively(head.next);
Console.WriteLine(head.val);
}
}
public static ListNode ReverseBetween(ListNode head, int m, int n)
{
//记录断开链表的四个位置
ListNode ansFirst = null;
ListNode first = null;
ListNode end = null;
ListNode ansEnd = null;
ListNode ansHead = head;
int i = 1;
while (head != null)
{
if (i == m - 1)
ansFirst = head;
if (i == m)
first = head;
if (i == n)
end = head;
if (i == n + 1)
ansEnd = head;
i++;
head = head.next;
}
end.next = null;
//开始翻转链表，采用头插法
ListNode temp = null;
ListNode localHead = null;
while (first != null)
{
temp = first.next;
first.next = localHead;
localHead = first;
first = temp;
}//翻转完成
first = localHead;
while (localHead.next != null)
{
localHead = localHead.next;
}
end = localHead;
//再次将链表接上
if (ansFirst!=null)
ansFirst.next = first;
end.next = ansEnd;
if (m == 1)
return first;
else
return ansHead;
}
