递归
class Solution {
public:
ListNode* reverseList(ListNode* head) {
if(head == nullptr || head->next == nullptr)
return head;
ListNode* next = head->next;
ListNode* ret = reverseList(head->next);
next->next = head;
head->next = nullptr;
return ret;
}
};
迭代
class Solution {
public:
ListNode* reverseList(ListNode* head) {
if(head == nullptr || head->next == nullptr)
return head;
ListNode *prev=nullptr,*curr=head,*next=nullptr;
while(curr!=nullptr) {
next = curr->next;
curr->next = prev;
prev = curr;
curr = next;
}
return prev;
}
};