BM1 反转链表

struct ListNode* ReverseList(struct ListNode* head ) {
    if(head==NULL) return head;
    struct ListNode *p,*tmpNode；
    tmpNode = (struct ListNode*)malloc(sizeof(struct ListNode));
    tmpNode->next = NULL;
    while(head != NULL)
    {
        p = head;
        head = head->next;
        p->next = tmpNode->next;
        tmpNode->next = p; 
    }
    return tmpNode->next;    
}