E_206_ReverseLinkedList.java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode reverseList(ListNode head) {
        
        ListNode header=null;
        while(head!=null){
            ListNode next=head.next;
            head.next=header;
            header=head;
            head=next;
            
        }
        return header;
    }     
}