题解 | #链表内指定区间反转#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 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
 */
struct ListNode* reverseBetween(struct ListNode* head, int m, int n ) {
    // write code here
    struct ListNode* start = head;
    struct ListNode* end = head;
    struct ListNode* tmp = head;
    struct ListNode* pre = (struct ListNode*)malloc(sizeof(struct ListNode));
    struct ListNode* cur;

    if(m == n)
    {
        return head;
    }

    
    pre->next = head;

    int p = m-1;
    int q = n-1;


    while(p--)
    {
        printf("p %d\n",p);
        if(m != 1)
        {
            pre = pre->next;
        }
        printf("pre %d\n",pre->val);
    }
    

    while(q--)
    {
        printf("q %d\n",q);
        if(end->next != NULL)
        {
            end = end->next;
        }
        printf("end %d\n",end->val);
    }

    while((pre->next != end) && (pre != end))
    {

        cur = pre->next;
        printf("cur %d\n",cur->val);

        pre->next = cur->next;
        cur->next = end->next;
        end->next = cur;
    }

    if(m == 1)
    {
        head = pre->next;
    }

    
// while(tmp != NULL)
// {
//     printf("result %d\n", tmp->val);
//     tmp = tmp->next;
// }
    return head;
}