题解 | #链表内指定区间反转#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 *	ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head ListNode类 
     * @param m int整型 
     * @param n int整型 
     * @return ListNode类
     */
    ListNode* reverseBetween(ListNode* head, int m, int n) {
        // write code here
        auto* new_head = new ListNode(-1);
        new_head->next = head;
        ListNode* cur = head;
        ListNode* pre = new_head;
        for (int i = 0; i < m - 1; i++) {
            cur = cur->next;
            pre = pre->next;
        }
        int i = m;
        while (cur && i < n) {
            ListNode* cur_next_next = cur->next->next;
            cur->next->next = pre->next;
            pre->next = cur->next;
            cur->next = cur_next_next;
            i++;
        }

        return new_head->next;
    }
};