反转从位置 m 到 n 的链表。请使用一趟扫描完成反转。
说明:
1 ≤ m ≤ n ≤ 链表长度。示例:
输入: 1->2->3->4->5->NULL, m = 2, n = 4
输出: 1->4->3->2->5->NULL来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/reverse-linked-list-ii
著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。
解法:
class Solution {
public:
ListNode *reverseBetween(ListNode *head, int m, int n)
{
ListNode *dummy = new ListNode(-1), *pre = dummy;
dummy->next = head;
for (int i = 0; i < m - 1; ++i)
pre = pre->next;
ListNode *cur = pre->next;
for (int i = m; i < n; ++i)
{
ListNode *t = cur->next;
cur->next = t->next;
t->next = pre->next;
pre->next = t;
}
return dummy->next;
}
};