Algorithms/stack/Java/Stack.java at master · Janitha133/Algorithms · GitHub

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importjava.util.NoSuchElementException;

publicclassStack<Item>{
privateintsize; // size of the Stack
privateNodefirst; // top of Stack

privateclassNode {
privateItemitem;
privateNodenext;
 }

/**
 * Creates an empty Stack instance
 */
publicStack() {
first = null;
size = 0;
 }

/**
 * Returns whether the Stack is empty or not.
 *
 * @return true if the Stack is empty, otherwise false.
 */
publicbooleanisEmpty() {
returnfirst == null;
 }

/**
 * Returns the amount of times in this Stack.
 *
 * @return the amount of times in this Stack.
 */
publicintgetSize() {
returnsize;
 }

/**
 * Add an item to this Stack.
 *
 * @param item the item to add.
 */
publicvoidpush(Itemitem) {
NodeoldFirst = first;
first = newNode();
first.item = item;
first.next = oldFirst;
size++;
 }

/**
 * Returns and removes the item on the top of this Stack.
 *
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempop() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
Itemitem = first.item;
first = first.next;
size--;
returnitem;
 }


/**
 * Returns the top item of the Stack, without removing it.
 *
 * @return the item on top of this Stack
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempeek() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
returnfirst.item;
 }

/**
 * Example usage
 */
publicstaticvoidmain(String[] args) throwsNoSuchElementException {
Stack<String> Stack = newStack<String>();
Stack.push("Hello World");
System.out.println(Stack.peek()); // "Hello World"
Stack.push("I am on the top now");
System.out.println(Stack.peek()); // "I am on the top now"
System.out.println(Stack.pop()); // "I am on the top now"
System.out.println(Stack.peek()); // "Hello World
 }
}
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importjava.util.NoSuchElementException;

publicclassStack<Item>{
privateintsize; // size of the Stack
privateNodefirst; // top of Stack

privateclassNode {
privateItemitem;
privateNodenext;
 }

/**
 * Creates an empty Stack instance
 */
publicStack() {
first = null;
size = 0;
 }

/**
 * Returns whether the Stack is empty or not.
 *
 * @return true if the Stack is empty, otherwise false.
 */
publicbooleanisEmpty() {
returnfirst == null;
 }

/**
 * Returns the amount of times in this Stack.
 *
 * @return the amount of times in this Stack.
 */
publicintgetSize() {
returnsize;
 }

/**
 * Add an item to this Stack.
 *
 * @param item the item to add.
 */
publicvoidpush(Itemitem) {
NodeoldFirst = first;
first = newNode();
first.item = item;
first.next = oldFirst;
size++;
 }

/**
 * Returns and removes the item on the top of this Stack.
 *
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempop() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
Itemitem = first.item;
first = first.next;
size--;
returnitem;
 }


/**
 * Returns the top item of the Stack, without removing it.
 *
 * @return the item on top of this Stack
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempeek() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
returnfirst.item;
 }

/**
 * Example usage
 */
publicstaticvoidmain(String[] args) throwsNoSuchElementException {
Stack<String> Stack = newStack<String>();
Stack.push("Hello World");
System.out.println(Stack.peek()); // "Hello World"
Stack.push("I am on the top now");
System.out.println(Stack.peek()); // "I am on the top now"
System.out.println(Stack.pop()); // "I am on the top now"
System.out.println(Stack.peek()); // "Hello World
 }
}
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importjava.util.NoSuchElementException;

publicclassStack<Item>{
privateintsize; // size of the Stack
privateNodefirst; // top of Stack

privateclassNode {
privateItemitem;
privateNodenext;
 }

/**
 * Creates an empty Stack instance
 */
publicStack() {
first = null;
size = 0;
 }

/**
 * Returns whether the Stack is empty or not.
 *
 * @return true if the Stack is empty, otherwise false.
 */
publicbooleanisEmpty() {
returnfirst == null;
 }

/**
 * Returns the amount of times in this Stack.
 *
 * @return the amount of times in this Stack.
 */
publicintgetSize() {
returnsize;
 }

/**
 * Add an item to this Stack.
 *
 * @param item the item to add.
 */
publicvoidpush(Itemitem) {
NodeoldFirst = first;
first = newNode();
first.item = item;
first.next = oldFirst;
size++;
 }

/**
 * Returns and removes the item on the top of this Stack.
 *
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempop() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
Itemitem = first.item;
first = first.next;
size--;
returnitem;
 }


/**
 * Returns the top item of the Stack, without removing it.
 *
 * @return the item on top of this Stack
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempeek() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
returnfirst.item;
 }

/**
 * Example usage
 */
publicstaticvoidmain(String[] args) throwsNoSuchElementException {
Stack<String> Stack = newStack<String>();
Stack.push("Hello World");
System.out.println(Stack.peek()); // "Hello World"
Stack.push("I am on the top now");
System.out.println(Stack.peek()); // "I am on the top now"
System.out.println(Stack.pop()); // "I am on the top now"
System.out.println(Stack.peek()); // "Hello World
 }
}
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importjava.util.NoSuchElementException;

publicclassStack<Item>{
privateintsize; // size of the Stack
privateNodefirst; // top of Stack

privateclassNode {
privateItemitem;
privateNodenext;
 }

/**
 * Creates an empty Stack instance
 */
publicStack() {
first = null;
size = 0;
 }

/**
 * Returns whether the Stack is empty or not.
 *
 * @return true if the Stack is empty, otherwise false.
 */
publicbooleanisEmpty() {
returnfirst == null;
 }

/**
 * Returns the amount of times in this Stack.
 *
 * @return the amount of times in this Stack.
 */
publicintgetSize() {
returnsize;
 }

/**
 * Add an item to this Stack.
 *
 * @param item the item to add.
 */
publicvoidpush(Itemitem) {
NodeoldFirst = first;
first = newNode();
first.item = item;
first.next = oldFirst;
size++;
 }

/**
 * Returns and removes the item on the top of this Stack.
 *
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempop() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
Itemitem = first.item;
first = first.next;
size--;
returnitem;
 }


/**
 * Returns the top item of the Stack, without removing it.
 *
 * @return the item on top of this Stack
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempeek() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
returnfirst.item;
 }

/**
 * Example usage
 */
publicstaticvoidmain(String[] args) throwsNoSuchElementException {
Stack<String> Stack = newStack<String>();
Stack.push("Hello World");
System.out.println(Stack.peek()); // "Hello World"
Stack.push("I am on the top now");
System.out.println(Stack.peek()); // "I am on the top now"
System.out.println(Stack.pop()); // "I am on the top now"
System.out.println(Stack.peek()); // "Hello World
 }
}
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importjava.util.NoSuchElementException;

publicclassStack<Item>{
privateintsize; // size of the Stack
privateNodefirst; // top of Stack

privateclassNode {
privateItemitem;
privateNodenext;
 }

/**
 * Creates an empty Stack instance
 */
publicStack() {
first = null;
size = 0;
 }

/**
 * Returns whether the Stack is empty or not.
 *
 * @return true if the Stack is empty, otherwise false.
 */
publicbooleanisEmpty() {
returnfirst == null;
 }

/**
 * Returns the amount of times in this Stack.
 *
 * @return the amount of times in this Stack.
 */
publicintgetSize() {
returnsize;
 }

/**
 * Add an item to this Stack.
 *
 * @param item the item to add.
 */
publicvoidpush(Itemitem) {
NodeoldFirst = first;
first = newNode();
first.item = item;
first.next = oldFirst;
size++;
 }

/**
 * Returns and removes the item on the top of this Stack.
 *
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempop() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
Itemitem = first.item;
first = first.next;
size--;
returnitem;
 }


/**
 * Returns the top item of the Stack, without removing it.
 *
 * @return the item on top of this Stack
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempeek() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
returnfirst.item;
 }

/**
 * Example usage
 */
publicstaticvoidmain(String[] args) throwsNoSuchElementException {
Stack<String> Stack = newStack<String>();
Stack.push("Hello World");
System.out.println(Stack.peek()); // "Hello World"
Stack.push("I am on the top now");
System.out.println(Stack.peek()); // "I am on the top now"
System.out.println(Stack.pop()); // "I am on the top now"
System.out.println(Stack.peek()); // "Hello World
 }
}
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importjava.util.NoSuchElementException;

publicclassStack<Item>{
privateintsize; // size of the Stack
privateNodefirst; // top of Stack

privateclassNode {
privateItemitem;
privateNodenext;
 }

/**
 * Creates an empty Stack instance
 */
publicStack() {
first = null;
size = 0;
 }

/**
 * Returns whether the Stack is empty or not.
 *
 * @return true if the Stack is empty, otherwise false.
 */
publicbooleanisEmpty() {
returnfirst == null;
 }

/**
 * Returns the amount of times in this Stack.
 *
 * @return the amount of times in this Stack.
 */
publicintgetSize() {
returnsize;
 }

/**
 * Add an item to this Stack.
 *
 * @param item the item to add.
 */
publicvoidpush(Itemitem) {
NodeoldFirst = first;
first = newNode();
first.item = item;
first.next = oldFirst;
size++;
 }

/**
 * Returns and removes the item on the top of this Stack.
 *
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempop() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
Itemitem = first.item;
first = first.next;
size--;
returnitem;
 }


/**
 * Returns the top item of the Stack, without removing it.
 *
 * @return the item on top of this Stack
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempeek() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
returnfirst.item;
 }

/**
 * Example usage
 */
publicstaticvoidmain(String[] args) throwsNoSuchElementException {
Stack<String> Stack = newStack<String>();
Stack.push("Hello World");
System.out.println(Stack.peek()); // "Hello World"
Stack.push("I am on the top now");
System.out.println(Stack.peek()); // "I am on the top now"
System.out.println(Stack.pop()); // "I am on the top now"
System.out.println(Stack.peek()); // "Hello World
 }
}
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importjava.util.NoSuchElementException;

publicclassStack<Item>{
privateintsize; // size of the Stack
privateNodefirst; // top of Stack

privateclassNode {
privateItemitem;
privateNodenext;
 }

/**
 * Creates an empty Stack instance
 */
publicStack() {
first = null;
size = 0;
 }

/**
 * Returns whether the Stack is empty or not.
 *
 * @return true if the Stack is empty, otherwise false.
 */
publicbooleanisEmpty() {
returnfirst == null;
 }

/**
 * Returns the amount of times in this Stack.
 *
 * @return the amount of times in this Stack.
 */
publicintgetSize() {
returnsize;
 }

/**
 * Add an item to this Stack.
 *
 * @param item the item to add.
 */
publicvoidpush(Itemitem) {
NodeoldFirst = first;
first = newNode();
first.item = item;
first.next = oldFirst;
size++;
 }

/**
 * Returns and removes the item on the top of this Stack.
 *
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempop() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
Itemitem = first.item;
first = first.next;
size--;
returnitem;
 }


/**
 * Returns the top item of the Stack, without removing it.
 *
 * @return the item on top of this Stack
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempeek() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
returnfirst.item;
 }

/**
 * Example usage
 */
publicstaticvoidmain(String[] args) throwsNoSuchElementException {
Stack<String> Stack = newStack<String>();
Stack.push("Hello World");
System.out.println(Stack.peek()); // "Hello World"
Stack.push("I am on the top now");
System.out.println(Stack.peek()); // "I am on the top now"
System.out.println(Stack.pop()); // "I am on the top now"
System.out.println(Stack.peek()); // "Hello World
 }
}
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importjava.util.NoSuchElementException;

publicclassStack<Item>{
privateintsize; // size of the Stack
privateNodefirst; // top of Stack

privateclassNode {
privateItemitem;
privateNodenext;
 }

/**
 * Creates an empty Stack instance
 */
publicStack() {
first = null;
size = 0;
 }

/**
 * Returns whether the Stack is empty or not.
 *
 * @return true if the Stack is empty, otherwise false.
 */
publicbooleanisEmpty() {
returnfirst == null;
 }

/**
 * Returns the amount of times in this Stack.
 *
 * @return the amount of times in this Stack.
 */
publicintgetSize() {
returnsize;
 }

/**
 * Add an item to this Stack.
 *
 * @param item the item to add.
 */
publicvoidpush(Itemitem) {
NodeoldFirst = first;
first = newNode();
first.item = item;
first.next = oldFirst;
size++;
 }

/**
 * Returns and removes the item on the top of this Stack.
 *
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempop() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
Itemitem = first.item;
first = first.next;
size--;
returnitem;
 }


/**
 * Returns the top item of the Stack, without removing it.
 *
 * @return the item on top of this Stack
 * @throws NoSuchElementException if this Stack is empty
 */
publicItempeek() throwsNoSuchElementException{
if (isEmpty()) thrownewNoSuchElementException("Stack underflow");
returnfirst.item;
 }

/**
 * Example usage
 */
publicstaticvoidmain(String[] args) throwsNoSuchElementException {
Stack<String> Stack = newStack<String>();
Stack.push("Hello World");
System.out.println(Stack.peek()); // "Hello World"
Stack.push("I am on the top now");
System.out.println(Stack.peek()); // "I am on the top now"
System.out.println(Stack.pop()); // "I am on the top now"
System.out.println(Stack.peek()); // "Hello World
 }
}