Reverse Linked List

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* reverseList(ListNode* head) {
if(!head || !head->next)
{
return head;
}
ListNode * prev = head;
ListNode * curr = head->next;
head->next = nullptr;
while(curr->next)
{
ListNode * temp = curr->next;
curr->next = prev;
prev = curr;
curr = temp;
}
curr->next = prev;
return curr;
}
};