链表的头节点
1 struct ListNode
2 {
3 void* m_nKey;
4 ListNode* m_pNext;
5 };
常规实现
代码
ListNode* ReverseIteratively(ListNode* pHead)
{
ListNode* pReversedHead = NULL;
ListNode* pNode = pHead;
ListNode* pPrev = NULL;
while(pNode != NULL)
{
// get the next node, and save it at pNext
ListNode* pNext = pNode->m_pNext;
// if the next node is null, the currect is the end of original
// list, and it's the head of the reversed list
if(pNext == NULL)
pReversedHead = pNode;
// reverse the linkage between nodes
pNode->m_pNext = pPrev;
// move forward on the the list
pPrev = pNode;
pNode = pNext;
}
递归实现(不需要临时节点)
代码
1 ListNode* reverse_list( ListNode* head) //逆序
2 {
3 ListNode* new_head=head;
4 if(head==NULL || head->next==NULL)
5 return head;
6 new_head = reverse_list(head->next);
7 head->next->next=head;
8 head->next=NULL; //防止链表成为一个环，这是最关键的。
9 return new_head;
10 }