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
    if(head==NULL||head->next==NULL)
        return head;
    if(m==n)
        return head;
	/*
	*把第m个节点后的所有节点依次插入到第m个位置前
	*/
    struct ListNode* dummy = (struct ListNode*)malloc(sizeof(struct ListNode));
    dummy->val = 0;
    dummy->next = head; 
    struct ListNode* pPre = dummy;
    struct ListNode* pCur = head;
    //tmp指向要发转到最前的节点
    struct ListNode* pTmp = NULL;
    for(int i=0; i<m-1; i++)
    {
        pPre = pPre->next;
        pCur = pCur->next;
    }
    for(int i=0; i<n-m; i++)
    {
        pTmp = pCur->next;
        pCur->next = pCur->next->next;
        pTmp->next = pPre->next;
        pPre->next = pTmp;
    }
    return dummy->next;
}