链表倒序输出

/倒序链表法/
思路：将链表的指向颠倒一下再顺序输出
class Solution{
public:
vector<int> printListFromTailToHead(ListNode* head){
vector<int> a;
if (head != NULL)
{
if (head->next == NULL)
a.push_back(head->val);
else
{
struct ListNode *oldhead;
struct ListNode *curhead;
oldhead = NULL;
while (head->next != NULL)
{
curhead = head;
head = head->next;
curhead->next = oldhead;
oldhead = curhead;
}
head->next = oldhead;
while (head->next != NULL)
{
a.push_back(head->val);
head = head->next;
}
a.push_back(head->val);
}
}</int></int>

    return a;

}

};