LeetCode206

. Reverse Linked List

 

---

Reverse a singly linked list.

Example:

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

class Solution {
    public ListNode reverseList(ListNode head) {
        if(head == null || head.next == null)
            return head;
        ListNode pre = null;
        while(head != null){
            
            ListNode temp = head.next;
            head.next = pre;
            pre = head;
            head = temp;
        }
        return pre;
        
    }
}