[APS] Duplicate Deletion

//juni 2021 - termin 1

import java.util.NoSuchElementException;
import java.util.Scanner;

public class deleteDuplicates {
    public static void deleteDuplicates(SLL<Integer> lista, int key) {
        int i = 0, j = 0;
        SLLNode<Integer> temp = lista.getFirst();
        while (temp != null) {
            if (temp.element.equals(key)) {
                i++;
            }
            temp=temp.succ;
        }
        temp = lista.getFirst();
        while (temp!=null) {
            if (temp.element.equals(key)) {
                j++;
            }
            if (i>0 && i == j) {
                lista.delete(temp);
                break;
            }
            temp = temp.succ;
        }

    }

    public static void main(String[] args) {
        SLL<Integer> lista = new SLL<Integer>();
        Scanner input = new Scanner(System.in);
        int n = Integer.parseInt(input.nextLine());
        String[] broevi_lista = (input.nextLine().split("\\s+"));
        for (int i = 0; i < n; i++) {
            lista.insertLast(Integer.parseInt(broevi_lista[i]));
        }

        System.out.println("Vnesi kluch!");
        int key = Integer.parseInt(input.nextLine());
        deleteDuplicates(lista, key);
        System.out.println(lista);


    }
}

class SLLNode<E>
{
    protected E element;
    protected SLLNode<E> succ;

    public SLLNode(E elem, SLLNode<E> succ) {
        this.element = elem;
        this.succ = succ;
    }

    @Override
    public String toString() {
        return element.toString();
    }
}

class SLL<E>
{
    private SLLNode<E> first;

    public SLL() {
        // Construct an empty SLL
        this.first = null;
    }

    public void deleteList() {
        first = null;
    }

    public int length() {
        int ret;
        if (first != null) {
            SLLNode<E> tmp = first;
            ret = 1;
            while (tmp.succ != null) {
                tmp = tmp.succ;
                ret++;
            }
            return ret;
        } else
            return 0;

    }

    @Override
    public String toString()
    {
        String ret = new String();
        if (first != null) {
            SLLNode<E> tmp = first;
            ret += tmp + " ";
            while (tmp.succ != null) {
                tmp = tmp.succ;
                ret += tmp + " ";
            }
        } else
            ret = "Prazna lista!!!";
        return ret;
    }

    public void insertFirst(E o) {
        SLLNode<E> ins = new SLLNode<E>(o, first);
        first = ins;
    }

    public void insertAfter(E o, SLLNode<E> node) {
        if (node != null) {
            SLLNode<E> ins = new SLLNode<E>(o, node.succ);
            node.succ = ins;
        } else {
            System.out.println("Dadenot jazol e null");
        }
    }

    public void insertBefore(E o, SLLNode<E> before) {

        if (first != null) {
            SLLNode<E> tmp = first;
            if(first==before){
                this.insertFirst(o);
                return;
            }
            //ako first!=before
            while (tmp.succ != before)
                tmp = tmp.succ;
            if (tmp.succ == before) {
                SLLNode<E> ins = new SLLNode<E>(o, before);
                tmp.succ = ins;
            } else {
                System.out.println("Elementot ne postoi vo listata");
            }
        } else {
            System.out.println("Listata e prazna");
        }
    }

    public void insertLast(E o) {
        if (first != null) {
            SLLNode<E> tmp = first;
            while (tmp.succ != null)
                tmp = tmp.succ;
            SLLNode<E> ins = new SLLNode<E>(o, null);
            tmp.succ = ins;
        } else {
            insertFirst(o);
        }
    }

    public E deleteFirst() {
        if (first != null) {
            SLLNode<E> tmp = first;
            first = first.succ;
            return tmp.element;
        } else {
            System.out.println("Listata e prazna");
            return null;
        }
    }

    public E delete(SLLNode<E> node) {
        if (first != null) {
            SLLNode<E> tmp = first;
            if(first ==node){
                return this.deleteFirst();
            }
            while (tmp.succ != node && tmp.succ.succ != null)
                tmp = tmp.succ;
            if (tmp.succ == node) {
                tmp.succ = tmp.succ.succ;
                return node.element;
            } else {
                System.out.println("Elementot ne postoi vo listata");
                return null;
            }
        } else {
            System.out.println("Listata e prazna");
            return null;
        }

    }

    public SLLNode<E> getFirst() {
        return first;
    }

    public SLLNode<E> find(E o) {
        if (first != null) {
            SLLNode<E> tmp = first;
            while (tmp.element != o && tmp.succ != null)
                tmp = tmp.succ;
            if (tmp.element == o) {
                return tmp;
            } else {
                System.out.println("Elementot ne postoi vo listata");
            }
        } else {
            System.out.println("Listata e prazna");
        }
        return first;
    }


}

//Test Case #1
//6
//1 2 3 5 2 10
//2

//1 2 3 5 10

//Test Case #2
//10
//9 3 3 8 6 2 9 3 5 9
//3

//9 3 3 8 6 2 9 5 9

//Test Case #3
//9
//1 3 3 4 6 2 7 3 5
//11

//1 3 3 4 6 2 7 3 5