迭代法:
class Solution {
public:
ListNode* reverseList(ListNode* head) {
ListNode* pre = NULL;
while (head) {
ListNode* next = head -> next;
head -> next = pre;
pre = head;
head = next;
}
return pre;
}
};
递归法：
class Solution {
public:
ListNode* reverseList(ListNode* head) {
if (!head || !(head -> next)) return head;
ListNode* node = reverseList(head -> next);
head -> next -> next = head;
head -> next = NULL;
return node;
}
};
