//Print a LinkedList to check the result
public static void PrintList(ListNode head){
Console.WriteLine(" ");
while(head!=null){
Console.Write (head.val + "->");
head = head.next;
}
}
//Reverse LinkedList
public static ListNode ReverseList(ListNode head){
if(head==null) return null;
ListNode prev = null;
ListNode curr = head;
ListNode next;
while (curr != null) {
next = curr.next;
curr.next = prev;
prev = curr;
curr = next;
}
return prev; //after the while loop, curr must be null, so return prev!
}
public static void Main (string[] args)
{
ListNode l1 = new ListNode (1);
ListNode l2 = new ListNode (2);
ListNode l3 = new ListNode (3);
ListNode l4 = new ListNode (4);
ListNode l5 = new ListNode (5);
l1.next = l2;
l2.next = l3;
l3.next = l4;
l4.next = l5;
Solution.PrintList (l1);
Solution.PrintList (Solution.ReverseList (l1));
}
public ListNode(int v){
this.val = v;
this.next = null;
}
public ListNode(int val = 0, ListNode next = null)
{
this.val = val;
this.next = next;
}