題目：

題解：

class Solution {
public:ListNode *reverseBetween(ListNode *head, int left, int right) {// 設置 dummyNode 是這一類問題的一般做法ListNode *dummyNode = new ListNode(-1);dummyNode->next = head;ListNode *pre = dummyNode;for (int i = 0; i < left - 1; i++) {pre = pre->next;}ListNode *cur = pre->next;ListNode *next;for (int i = 0; i < right - left; i++) {next = cur->next;cur->next = next->next;next->next = pre->next;pre->next = next;}return dummyNode->next;}
};