DSA-in-Java/LL.java at main · shajiyakhan1309/DSA-in-Java · GitHub

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class LL {
    Node head;
private int size;
LL(){
    size = 0;
}

class Node{
    String data;
    Node next;


    Node(String data){
        this.data = data;
        this.next = null;
        size++;
    }
}

public void addFirst(String data){
    Node newNode = new Node(data);
    if(head == null){
        head = newNode;
        return;
    }

    newNode.next = head;
    head = newNode;

}

public void addLast(String data){
    Node newNode = new Node(data);
    if(head == null){
        head = newNode;
        return;
    }
    Node currNode = head;
    while(currNode.next!=null){
        currNode = currNode.next;
    }
    currNode.next = newNode;
}

public void deleteFirst(){
    if(head == null){
        System.out.println("Underflow");
    }
    size--;
    head = head.next;

}

public void deleteLast(){
    if(head == null){
        System.out.println("Underflow");
    }
    size--;
    if(head.next == null){
        head = null;
    }
    Node secondLast = head;
    Node lastNode = head.next;
    while(lastNode.next!= null){
        lastNode = lastNode.next;
        secondLast = secondLast.next;
    }

    secondLast.next = null;

}

public void printList(){
    if(head==null){
        System.out.println("Underflow");
        return;
    }
    Node currNode = head;
    while(currNode!=null){

        System.out.print(currNode.data + "-> ");
        currNode = currNode.next;
    }
    System.out.println("NULL");
}

public int getSize(){
    return size;
}
    public static void main(String[] args) {
        LL list = new LL();
        list.addLast("this");
        list.addLast("is");
        list.addLast("a");
        list.addLast("linked");
        list.addLast("list");
        list.printList();

        list.deleteFirst();
        list.printList();

        list.deleteLast();
        list.printList();

        System.out.println(list.getSize());

    }
}