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Implementato alcuni esercizi

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Giovanni Di Grezia
2014-04-14 01:11:38 +02:00
parent cafb12ea9f
commit b22cd894c1
5 changed files with 433 additions and 0 deletions
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65
esercizi/QStack.java Normal file
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package esercizi;
import exceptions.EmptyStackException;
import queue.NodeQueue;
import stack.Stack;
/**
* Created with MONSTER.
* User: xgiovio
* Date: 13/04/2014
* Time: 23:48
*/
// emulate a stack with a queue
public class QStack<E> implements Stack<E> {
NodeQueue<E> a = new NodeQueue<E>();
@Override
public void push(E element) {
a.enqueue(element);
}
@Override
public E top() throws EmptyStackException {
if (a.isEmpty()){
throw new EmptyStackException();
}else {
E t;
for (int i = 0 ;i<a.size() - 1;i++){
a.enqueue(a.dequeue());
}
t = a.front();
a.enqueue(a.dequeue());
return t;
}
}
@Override
public E pop() throws EmptyStackException {
if (a.isEmpty()){
throw new EmptyStackException();
}else {
for (int i = 0 ;i<a.size() - 1;i++){
a.enqueue(a.dequeue());
}
return a.dequeue();
}
}
@Override
public boolean isEmpty() {
return a.isEmpty();
}
@Override
public int size() {
return a.size();
}
@Override
public String toString() {
return a.toString();
}
}

85
esercizi/SQueue.java Normal file
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package esercizi;
import exceptions.EmptyQueueException;
import queue.Queue;
import sequence.ArraySequence;
import stack.ArrayStack;
/**
* Created with MONSTER.
* User: xgiovio
* Date: 13/04/2014
* Time: 23:01
*/
// queue emulated via 2 stacks
public class SQueue<E> implements Queue<E> {
private ArrayStack<E> accoda = new ArrayStack<E>();
private ArrayStack<E> decoda = new ArrayStack<E>();
@Override
public void enqueue(E element) {
accoda.push(element);
}
@Override
public E dequeue() throws EmptyQueueException {
if (accoda.isEmpty()){
throw new EmptyQueueException();
} else {
E temp;
int size = accoda.size();
for (int i = 0; i <size; i++) {
decoda.push(accoda.pop());
}
temp = decoda.pop();
size = decoda.size();
for (int i = 0; i < size; i++) {
accoda.push(decoda.pop());
}
return temp;
}
}
@Override
public E front() throws EmptyQueueException {
if (accoda.isEmpty()){
throw new EmptyQueueException();
} else {
E temp;
int size = accoda.size();
for (int i = 0; i <size; i++) {
decoda.push(accoda.pop());
}
temp = decoda.top();
size = decoda.size();
for (int i = 0; i < size; i++) {
accoda.push(decoda.pop());
}
return temp;
}
}
@Override
public boolean isEmpty() {
return accoda.isEmpty();
}
@Override
public int size() {
return accoda.size();
}
@Override
public String toString() {
return accoda.toString();
}
}

69
esercizi/start.java Normal file
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package esercizi;
/**
* Created with MONSTER.
* User: xgiovio
* Date: 13/04/2014
* Time: 22:18
*/
public class start {
public static void main(String[] args) {
System.out.println(static_methods.inverti("ehila"));
System.out.println(static_methods.checkParentheses("[()()()]([])"));
System.out.println (static_methods.isPalindrome("a"));
///////////// test squeue
SQueue<Integer> a = new SQueue<Integer>();
a.enqueue(5);
a.enqueue(10);
a.enqueue(20);
a.enqueue(30);
a.enqueue(40);
System.out.println (a);
System.out.println (a.front());
System.out.println (a.dequeue());
System.out.println (a);
a.enqueue(60);
System.out.println (a);
System.out.println (a.front());
System.out.println (static_methods.extract(a,0));
///////////// end test squeue
QStack<Integer> b = new QStack<Integer>();
b.push(1);
b.push(2);
b.push(3);
b.push(4);
System.out.println (b);
System.out.println (b.top());
System.out.println (b.top());
System.out.println (b.pop());
System.out.println (b);
System.out.println (b.top());
System.out.println (a);
System.out.println (static_methods.isContained(a,115));
System.out.println (a);
}
}

193
esercizi/static_methods.java Normal file
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package esercizi;
import queue.NodeQueue;
import queue.Queue;
import stack.ArrayStack;
import exceptions.*;
/**
* Created with MONSTER.
* User: xgiovio
* Date: 13/04/2014
* Time: 22:19
*/
public class static_methods {
// inver a string using a stack
public static String inverti (String s){
ArrayStack<Character> a = new ArrayStack<Character>();
for (int i = 0 ;i< s.length();i++){
a.push(s.charAt(i));
}
String to_return = "";
for (int i = 0 ;i< s.length();i++){
to_return += a.pop();
}
return to_return;
}
// verify is a string of [ and ( is correct using a stack
public static boolean checkParentheses (String s) {
ArrayStack<Character> a = new ArrayStack<Character>();
for (int i = 0 ; i< s.length();i++){
if (s.charAt(i) == '('){
a.push(s.charAt(i));
continue;
}
if (s.charAt(i) == ')'){
if (a.isEmpty() || a.top() != '('){
return false;
} else {
a.pop();
}
continue;
}
if (s.charAt(i) == '['){
if ( a.isEmpty() || a.top() != '(') {
a.push(s.charAt(i));
} else {
return false;
}
continue;
}
if (s.charAt(i) == ']'){
if (a.isEmpty() || a.top() != '['){
return false;
} else {
a.pop();
}
continue;
}
}
if (a.isEmpty()){
return true;
}else {
return false;
}
}
// verify is a string is palindrome using a stack
public static boolean isPalindrome (String s){
ArrayStack<Character> a = new ArrayStack<Character>();
if (s.length() < 2){
return true;
}else {
boolean pari;
if (s.length() % 2 == 0) {
pari = true;
} else {
pari = false;
}
for (int i= 0 ;i < s.length();i++){
if (!pari){
if (i <= s.length()/2){
a.push(s.charAt(i));
if (i == s.length()/2 ){
a.pop();
}
continue;
}
} else {
if (i <= (s.length()/2) -1){
a.push(s.charAt(i));
continue;
}
}
if (s.charAt(i) != a.pop()){
return false;
}
}
return true;
}
}
// extract the k element from a Queue Q. k should be >= 0
public static Integer extract (Queue<Integer> Q, int k) throws NotEnoughElements {
if (Q.size() <= k) {
throw new NotEnoughElements();
} else {
Integer t = null ;
for (int i = 0 ;i< Q.size();i++){
if (i == k){
t = Q.front();
}
Q.enqueue(Q.dequeue());
}
return t;
}
}
// invert a Queue without recursive methods
public static <E> void reverse (Queue<E> Q){
NodeQueue<E> newq = new NodeQueue<E>();
for (;Q.size()> 0;){
for (int i = 0;i< Q.size() - 1;i++){
Q.enqueue(Q.dequeue());
}
newq.enqueue(Q.dequeue());
}
int size = newq.size();
for (int i = 0;i<size;i++){
Q.enqueue(newq.dequeue());
}
}
// invert a Queue with recursion
public static <E> void recReverse (Queue<E> Q){
if (Q.size()>1){
E t = Q.dequeue();
recReverse(Q);
Q.enqueue(t);
}
}
// search element x in Queue Q . WARNING THIS FUNCTION ALTER THE ORIGINAL QUEUE Q
public static <E> boolean isContained (Queue<E>Q,E x){
if (Q.size() > 0){
E t = Q.dequeue();
if (t==x){
return true;
}
else{
return isContained(Q,x);
}
}else {
return false;
}
}
}

21
exceptions/NotEnoughElements.java Normal file
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package exceptions;
/**
* Thrown when a position is determined to be invalid.
* @author Roberto Tamassia, Michael Goodrich
*/
//Copyright (c) 2003 Brown University, Providence, RI
//Additional modifications and methods by xgiovio
public class NotEnoughElements extends RuntimeException {
public NotEnoughElements(String err) {
super(err);
}
public NotEnoughElements() {
super("NotEnoughElements");
}
}