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
 */
 void fanzhuan(struct ListNode * head,int m,int n)
 {
    struct ListNode * pre;
    struct ListNode * cur=head;
    struct ListNode * next;
    for(int i=0;i<n-m+1;i++)
    {
        next=cur->next;
        cur->next=pre;
        pre=cur;
        cur=next;
    }
 }
struct ListNode* reverseBetween(struct ListNode* head, int m, int n ) 
{
    int i;
    struct ListNode * dummy=(struct ListNode *)malloc(sizeof(struct ListNode));
    dummy->next=head;
    struct ListNode * pre=dummy;
    struct ListNode * start;
    struct ListNode * end=dummy;
    struct ListNode * last;
    for(i=0;i<m-1;i++)
    {
        pre=pre->next;
    }
    start=pre->next;
    for(i=0;i<n;i++)
    {
        end=end->next;
    }
    last=end->next;
    fanzhuan(start,m,n);
    pre->next=end;
    start->next=last;
    return dummy->next;
}