Anticlockwise spiral conversion of doubly linked list in scala

Scala program for Anticlockwise spiral conversion of doubly linked list. Here problem description and explanation.

``````// Scala program for
// Convert a doubly linked list anticlockwise spiral form

// This is Linked List Node
{
def this(data: Int)
{
this(data, null, null);
}
}
{
def this()
{
this(null, null);
}
// Insert new node at end position
def insert(value: Int): Unit = {
// Create a node
{
this.tail = node;
return;
}
// Add node at last position
this.tail.next = node;
node.prev = this.tail;
this.tail = node;
}
// Display node element of doubly linked list
def display(): Unit = {
{
}
else
{
// Get first node of linked list
while (temp != null)
{
// Display node value
print("  " + temp.data);
// Visit to next node
temp = temp.next;
}
// Get last node of linked list
temp = this.tail;
while (temp != null)
{
// Display node value
print("  " + temp.data);
// Visit to prev node
temp = temp.prev;
}
}
}
def spiralTransform(): Unit = {
{
return;
}
while (current != null && last != null)
{
if (current == last)
{
current.next = null;
current.prev = back;
this.tail = current;
// Set new last node
return;
}
else if (current.next == last)
{
current.next = null;
current.prev = last;
last.next = current;
last.prev = back;
// Set new last node
this.tail = current;
return;
}
auxiliary = current.next;
temp = last.prev;
current.prev = last;
last.next = current;
current.next = temp;
last.prev = back;
back = current;
current = auxiliary;
last = temp;
}
}
}
object Main
{
def main(args: Array[String]): Unit = {
// Insert following linked list nodes
dll.insert(1);
dll.insert(2);
dll.insert(3);
dll.insert(4);
dll.insert(5);
dll.insert(6);
dll.insert(7);
dll.insert(8);
dll.insert(9);
println("\nBefore anticlockwise spiral conversion");
// Display all node
dll.display();
println("\nAfter anticlockwise spiral conversion");
dll.spiralTransform();
dll.display();
}
}``````

Output

``````Before anticlockwise spiral conversion
Linked List Head to Tail :  1  2  3  4  5  6  7  8  9
Linked List Tail to Head :  9  8  7  6  5  4  3  2  1
After anticlockwise spiral conversion
Linked List Head to Tail :  9  1  8  2  7  3  6  4  5
Linked List Tail to Head :  5  4  6  3  7  2  8  1  9``````

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