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- import java.io.BufferedReader;
- import java.io.IOException;
- import java.io.InputStreamReader;
- class DLLNode<E> {
- protected E element;
- protected DLLNode<E> pred, succ;
- public DLLNode(E elem, DLLNode<E> pred, DLLNode<E> succ) {
- this.element = elem;
- this.pred = pred;
- this.succ = succ;
- }
- @Override
- public String toString() {
- return element.toString() ;
- }
- }
- class DLL<E> {
- private DLLNode<E> first, last;
- public DLL() {
- // Construct an empty SLL
- this.first = null;
- this.last = null;
- }
- public void deleteList() {
- first = null;
- last = null;
- }
- public int length() {
- int ret;
- if (first != null) {
- DLLNode<E> tmp = first;
- ret = 1;
- while (tmp.succ != null) {
- tmp = tmp.succ;
- ret++;
- }
- return ret;
- } else
- return 0;
- }
- public void insertFirst(E o) {
- DLLNode<E> ins = new DLLNode<E>(o, null, first);
- if (first == null)
- last = ins;
- else
- first.pred = ins;
- first = ins;
- }
- public void insertLast(E o) {
- if (first == null)
- insertFirst(o);
- else {
- DLLNode<E> ins = new DLLNode<E>(o, last, null);
- last.succ = ins;
- last = ins;
- }
- }
- public void insertAfter(E o, DLLNode<E> after) {
- if (after == last) {
- insertLast(o);
- return;
- }
- DLLNode<E> ins = new DLLNode<E>(o, after, after.succ);
- after.succ.pred = ins;
- after.succ = ins;
- }
- public void insertBefore(E o, DLLNode<E> before) {
- if (before == first) {
- insertFirst(o);
- return;
- }
- DLLNode<E> ins = new DLLNode<E>(o, before.pred, before);
- before.pred.succ = ins;
- before.pred = ins;
- }
- public E deleteFirst() {
- if (first != null) {
- DLLNode<E> tmp = first;
- first = first.succ;
- if (first != null) first.pred = null;
- if (first == null)
- last = null;
- return tmp.element;
- } else
- return null;
- }
- public E deleteLast() {
- if (first != null) {
- if (first.succ == null)
- return deleteFirst();
- else {
- DLLNode<E> tmp = last;
- last = last.pred;
- last.succ = null;
- return tmp.element;
- }
- }
- // else throw Exception
- return null;
- }
- @Override
- public String toString() {
- String ret = new String();
- if (first != null) {
- DLLNode<E> tmp = first;
- ret += tmp ;
- while (tmp.succ != null) {
- tmp = tmp.succ;
- ret += tmp ;
- }
- } else
- ret = "Prazna lista!!!";
- return ret;
- }
- public DLLNode<E> getFirst() {
- return first;
- }
- public DLLNode<E> getLast() {
- return last;
- }
- }
- public class PalindromeDLL {
- public static int Prebroj(DLL<Integer> lista1)
- {
- DLLNode<Integer> p = lista1.getFirst();
- DLLNode<Integer> q = lista1.getLast();
- int n = lista1.length();
- int middle = (int)Math.ceil(n/2.0);
- for(int i = 1 ; i <=middle ; i ++){
- if(p.element==q.element){
- p=p.succ;
- q=q.pred;
- }
- else
- return -1;
- }
- return 1;
- }
- public static void main(String [] args) throws IOException
- {
- BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
- String s;
- int n ;
- int broj;
- String [] str;
- DLL<Integer>lista=new DLL<Integer>();
- s = br.readLine();
- n = Integer.parseInt(s);
- s = br.readLine();
- str = s.split(" ");
- for(int i = 0 ; i < n ; i ++){
- broj = Integer.parseInt(str[i]);
- lista.insertLast(broj);
- }
- s = br.readLine();
- System.out.println(Prebroj(lista));
- }
- }
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