//here's a singly linked list program with functions. However, I don't kbow how to add function #7 wherein
//the position of the maximum number in the list should be displayed.. :(
import java.util.Scanner;
class Node
{
protected int data;
protected Node link;
protected int next_num;
public Node()
{
link = null;
data = 0;
}
public Node(int d,Node n)
{
data = d;
link = n;
}
public void setLink(Node n)
{
link = n;
}
public void setData(int d)
{
data = d;
}
public Node getLink()
{
return link;
}
public int getData()
{
return data;
}
public int next()
{
return next_num;
}
}
class linkedList
{
protected Node start;
protected Node end ;
public int size ;
public int largest;
public int ctr;
public linkedList()
{
start = null;
end = null;
size = 0;
}
public int getLargest(){
largest=start.getData();
Node next=start.getLink();
for(ctr=0;ctr<size;ctr++){
if(largest<next.getData()){
largest=next.getData();
}
next=next.getLink();
}
return ctr;
}
public boolean isEmpty()
{
return start == null;
}
public int getSize()
{
return size;
}
public void insertAtStart(int val)
{
Node nptr = new Node(val, null);
size++ ;
if(start == null)
{
start = nptr;
end = start;
}
else
{
nptr.setLink(start);
start = nptr;
}
}
public void insertAtEnd(int val)
{
Node nptr = new Node(val,null);
size++ ;
if(start == null)
{
start = nptr;
end = start;
}
else
{
end.setLink(nptr);
end = nptr;
}
}
public void insertAtPos(int val , int pos)
{
Node nptr = new Node(val, null);
Node ptr = start;
pos = pos - 1 ;
for (int i = 1; i < size; i++)
{
if (i == pos)
{
Node tmp = ptr.getLink() ;
ptr.setLink(nptr);
nptr.setLink(tmp);
break;
}
ptr = ptr.getLink();
}
size++ ;
}
public void deleteAtPos(int pos)
{
if (pos == 1)
{
start = start.getLink();
size--;
return ;
}
if (pos == size)
{
Node s = start;
Node t = start;
while (s != end)
{
t = s;
s = s.getLink();
}
end = t;
end.setLink(null);
size --;
return;
}
Node ptr = start;
pos = pos - 1 ;
for (int i = 1; i < size - 1; i++)
{
if (i == pos)
{
Node tmp = ptr.getLink();
tmp = tmp.getLink();
ptr.setLink(tmp);
break;
}
ptr = ptr.getLink();
}
size-- ;
}
public void display()
{
System.out.print("\nSingly Linked List = ");
if (size == 0)
{
System.out.print("empty\n");
return;
}
if (start.getLink() == null)
{
System.out.println(start.getData() );
return;
}
Node ptr = start;
System.out.print(start.getData()+ "->");
ptr = start.getLink();
while (ptr.getLink() != null)
{
System.out.print(ptr.getData()+ "->");
ptr = ptr.getLink();
}
System.out.print(ptr.getData()+ "\n");
}
}
public class SinglyLinkedList
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
linkedList list = new linkedList();
System.out.println("Singly Linked List Test\n");
char ch;
do
{
System.out.println("\nSingly Linked List Operations\n");
System.out.println("1. insert at begining");
System.out.println("2. insert at end");
System.out.println("3. insert at position");
System.out.println("4. delete at position");
System.out.println("5. check empty");
System.out.println("6. get size");
System.out.println("7. locate for the largest element.");
int choice = scan.nextInt();
switch (choice)
{
case 1 :
System.out.println("Enter integer element to insert");
list.insertAtStart( scan.nextInt() );
break;
case 2 :
System.out.println("Enter integer element to insert");
list.insertAtEnd( scan.nextInt() );
break;
case 3 :
System.out.println("Enter integer element to insert");
int num = scan.nextInt() ;
System.out.println("Enter position");
int pos = scan.nextInt() ;
if (pos <= 1 || pos > list.getSize() )
System.out.println("Invalid position\n");
else
list.insertAtPos(num, pos);
break;
case 4 :
System.out.println("Enter position");
int p = scan.nextInt() ;
if (p < 1 || p > list.getSize() )
System.out.println("Invalid position\n");
else
list.deleteAtPos(p);
break;
case 5 :
System.out.println("Empty status = "+ list.isEmpty());
break;
case 6 :
System.out.println("Size = "+ list.getSize() +" \n");
break;
case 7:
System.out.println("position is at:"+list.getLargest());
break;
default :
System.out.println("Wrong Entry \n ");
break;
}
list.display();
System.out.println("\nDo you want to continue (Type y or n) \n");
ch = scan.next().charAt(0);
} while (ch == 'Y'|| ch == 'y');
}
}
