题解 | #反转链表#

/**
 * 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 
 * @return ListNode类
 */
struct ListNode* ReverseList(struct ListNode* head ) {
    struct ListNode *now;
    struct ListNode *pre;
    struct ListNode *last;
    if(head==NULL||head->next==NULL){
        return head;
    }
     now=head->next;
     head->next=NULL;
     last=head;
     while(now->next!=NULL){
        pre=now->next;
        now->next=last;
        last=now;
        now=pre;
     }
     now->next=last;
     return now;
}