Reverse a Singly linkedList

Problem statement: How to reverse a singly linked list.

//This is a simple linked list
class SimpleLinkedList
{
public SimpleLinkedList next;
public int value;
public SimpleLinkedList(int v)
{
value = v;
}
}


//This is how we reverse it
SimpleLinkedList reversethis(SimpleLinkedList input)
{
SimpleLinkedList a = null;
SimpleLinkedList b= input;
SimpleLinkedList c= input.next;

while (c != null)
{
b.next = a;

// Here a,b,c will MARCH TO NEXTs
a = b;
b = c;
c = c.next;
}

b.next = a;
return b;
}

//This is how we Fill , call , test it.
SimpleLinkedList root = new SimpleLinkedList(0);
SimpleLinkedList temp = root ;
for (int i = 1; i <= 10; i++)
{
temp.next = new SimpleLinkedList(i);
temp = temp.next;
}
label2.Text = label1.Text = "";
temp = root;
while (temp != null)
{
label1.Text += temp.value.ToString() + "\r\n";
temp = temp.next;
}



root = reversethis(root);
temp = root;
while (temp != null)
{
label2.Text += temp.value.ToString() + "\r\n";

temp = temp.next;
}

Interesting.

Lools like simplest reversal.

One more interesting thing in your function is

This is a way to find if the linked list is having a loop.
Typically

SimpleLinkedList root;

SimpleLinkedList temp = reverseit(root);
if(temp == root) THIS LINKEDLIST HAS A LOOP.

This is a destructive test on loopy linkedlist.

So remedy is calling it again
root = reverseit(root);

Someone recently asked how to reverse a circular linkedlist.

Above algorithm can be used--- Except that we will scan until we find the node where we started (Instead of searching for null)


A better solution can be simply put all the nodes into a stack. Then pop them until stack is empty and append it to the first one.