assignment

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k0rrluna 2025-04-25 19:51:03 +03:00
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commit 9e95d7d514
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//Note: We are using the class LinkedStack instead of
// the class OurStack that the book uses.
/**
A class that checks whether the parentheses, brackets, and braces
in a string occur in left/right pairs.
@author Frank M. Carrano, Timothy M. Henry
@version 5.0 */
public class LinkedStack<T> implements StackInterface<T>
{
private Node firstNode; // Reference to first node
private int numberOfEntries;
public LinkedStack()
{
firstNode = null;
numberOfEntries = 0;
} // end default constructor
/** Adds a new entry to the top of this stack.
@param newEntry An object to be added to the stack. */
public void push(T newEntry)
{
// Add to beginning of chain:
Node newNode = new Node(newEntry);
newNode.setNextNode(firstNode); // Make new node reference rest of chain
// (firstNode is null if chain is empty)
firstNode = newNode; // New node is at beginning of chain
numberOfEntries++;
}
/** Removes and returns this stack's top entry.
@return The object at the top of the stack.
@throws EmptyStackException if the stack is empty before the operation. */
public T pop()
{
T result = null;
if (firstNode != null)
{
Node removingNode = firstNode;
result = removingNode.getData();
firstNode = firstNode.getNextNode();
numberOfEntries--;
}
return result;
}
/** Retrieves this stack's top entry.
@return The object at the top of the stack.
@throws EmptyStackException if the stack is empty. */
public T peek()
{
T result = null;
if (firstNode != null)
result = firstNode.getData();
return result;
}
/** Detects whether this stack is empty.
@return True if the stack is empty. */
public boolean isEmpty()
{
return numberOfEntries == 0;
}
/** Removes all entries from this stack. */
public void clear()
{
firstNode = null;
}
// @author Frank M. Carrano, Timothy M. Henry
// @version 5.0 */
private class Node
{
private T data; // Entry in bag
private Node next; // Link to next node
private Node(T dataPortion)
{
this(dataPortion, null);
} // end constructor
private Node(T dataPortion, Node nextNode)
{
data = dataPortion;
next = nextNode;
} // end constructor
private T getData()
{
return data;
} // end getData
private void setData(T newData)
{
data = newData;
} // end setData
private Node getNextNode()
{
return next;
} // end getNextNode
private void setNextNode(Node nextNode)
{
next = nextNode;
} // end setNextNode
} // end Node
} // end LinkedStack

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public class Postfix {
public static String convertToPostfix(String infix) {
StackInterface<Character> operatorStack = new LinkedStack<>();
char[] postfixArray = new char[infix.length()]; // Max possible size
int postfixIndex = 0;
int index = 0;
char nextCharacter = ' ';
char topOperator = ' ';
while (index < infix.length()) {
nextCharacter = infix.charAt(index);
switch (nextCharacter) {
case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g': case 'h':
postfixArray[postfixIndex++] = nextCharacter;
break;
case '^':
operatorStack.push(nextCharacter);
break;
case '+': case '-': case '*': case '/':
while (!operatorStack.isEmpty() &&
!isBigger(nextCharacter, operatorStack.peek())) {
postfixArray[postfixIndex++] = operatorStack.pop();
}
operatorStack.push(nextCharacter);
break;
case '(':
operatorStack.push(nextCharacter);
break;
case ')':
topOperator = operatorStack.pop();
while (topOperator != '(') {
postfixArray[postfixIndex++] = topOperator;
topOperator = operatorStack.pop();
}
break;
default:
break;
}
index++;
}
while (!operatorStack.isEmpty()) {
postfixArray[postfixIndex++] = operatorStack.pop();
}
// Create string only from the used portion of the array
return new String(postfixArray, 0, postfixIndex);
}
// Rest of the class remains the same (isBigger, precedenceLevel, evaluatePostfix, etc.)
private static boolean isBigger(char ch1, char ch2) {
return precedenceLevel(ch1) > precedenceLevel(ch2);
}
private static int precedenceLevel(char op) {
switch (op) {
case '(': return 0;
case '+': case '-': return 1;
case '*': case '/': return 2;
case '^': return 3;
default: throw new IllegalArgumentException("Operator unknown: " + op);
}
}
public static int evaluatePostfix(String postfix) {
StackInterface<Integer> valueStack = new LinkedStack<>();
int index = 0;
char nextCharacter = ' ';
Integer operandTwo, operandOne;
int result;
while (index < postfix.length()) {
nextCharacter = postfix.charAt(index);
switch (nextCharacter) {
case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g': case 'h':
valueStack.push(getValue(nextCharacter));
break;
case '+': case '-': case '*': case '/': case '^':
operandTwo = valueStack.pop();
operandOne = valueStack.pop();
result = calculate(operandOne,operandTwo,nextCharacter);
valueStack.push(result);
break;
default: break;
}
index++;
}
return valueStack.peek();
}
private static Integer getValue(char op) {
Integer[] values = {2, 3, 4, 5, 6}; // a, b, c, d, e
return values[op-97];
}
private static Integer calculate(Integer opd1, Integer opd2, char opr) {
Integer intObj = 0;
switch (opr) {
case '+': intObj = opd1 + opd2; break;
case '-': intObj = opd1 - opd2; break;
case '*': intObj = opd1 * opd2; break;
case '/':
if (opd2.equals(0))
throw new ArithmeticException("Division by zero");
else
intObj = opd1 / opd2;
break;
case '^': intObj = (int) Math.pow(opd1, opd2); break;
default: break;
}
return intObj;
}
public static int evaluateInfix(String infix) {
StackInterface<Character> operatorStack = new LinkedStack<>();
StackInterface<Integer> valueStack = new LinkedStack<>();
int index = 0;
char nextCharacter = ' ';
char topOperator = ' ';
Integer operandTwo, operandOne;
int result;
while (index < infix.length()) {
nextCharacter = infix.charAt(index);
switch (nextCharacter) {
case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g': case 'h':
valueStack.push(getValue(nextCharacter));
break;
case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9':
valueStack.push(Character.getNumericValue(nextCharacter));
break;
case '^':
operatorStack.push(nextCharacter);
break;
case '+': case '-': case '*': case '/':
while (!operatorStack.isEmpty() &&
!isBigger(nextCharacter, operatorStack.peek())) {
topOperator = operatorStack.pop();
operandTwo = valueStack.pop();
operandOne = valueStack.pop();
result = calculate(operandOne,operandTwo,topOperator);
valueStack.push(result);
}
operatorStack.push(nextCharacter);
break;
case '(':
operatorStack.push(nextCharacter);
break;
case ')':
topOperator = operatorStack.pop();
while (topOperator != '(') {
operandTwo = valueStack.pop();
operandOne = valueStack.pop();
result = calculate(operandOne,operandTwo,topOperator);
valueStack.push(result);
topOperator = operatorStack.pop();
}
break;
default: break;
}
index++;
}
while (!operatorStack.isEmpty()) {
topOperator = operatorStack.pop();
operandTwo = valueStack.pop();
operandOne = valueStack.pop();
result = calculate(operandOne,operandTwo,topOperator);
valueStack.push(result);
}
return valueStack.peek();
}
}

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// @author Frank M. Carrano
// @author Timothy M. Henry
// @version 5.0
public class PostfixTest
{
public static void main(String arg[])
{
// Test convertToPostfix
System.out.println("Testing convertToPostfix");
String[] expressions = {"(a+b)/(c-d)","a/(b-c)*d","a-(b/(c-d)*e+f)^g",
"(a-b*c)/(d*e^f*g+h)"};
String[] qNums = {"a", "b", "c", "d"};
for (int i = 0; i < expressions.length; i++)
{
String postfix = Postfix.convertToPostfix(expressions[i]);
System.out.println(qNums[i]+". " + expressions[i] + " is converted to " + postfix);
}
System.out.println();
// Test evaluatePostfix
System.out.println("Testing evaluatePostfix");
String[] postfixes = {"a e + b d - /", "a b c * d * -","a b c - / d *",
"e b c a ^ * + d -"};
for (int i = 0; i < postfixes.length; i++)
{
int evaluation = Postfix.evaluatePostfix(postfixes[i]);
System.out.println(qNums[i]+". " + postfixes[i] + " is evaluated as " + evaluation);
}
System.out.println();
// Test evaluateInfix
System.out.println("Testing evaluateInfix");
String[] infixes = {"a+b*c-9", "(a+ e)/ (b- d)","a+(b+c*d)-e/2",
"e-b*c^a+d"};
for (int i = 0; i < postfixes.length; i++)
{
int evaluation = Postfix.evaluateInfix(infixes[i]);
System.out.println(qNums[i]+". " + infixes[i] + " is evaluated as " + evaluation);
}
}
}

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/**
An interface for the ADT stack.
@author Frank M. Carrano
@author Timothy M. Henry
@version 5.0
*/
public interface StackInterface<T>
{
/** Adds a new entry to the top of this stack.
@param newEntry An object to be added to the stack. */
public void push(T newEntry);
/** Removes and returns this stack's top entry.
@return The object at the top of the stack.
@throws EmptyStackException if the stack is empty before the operation. */
public T pop();
/** Retrieves this stack's top entry.
@return The object at the top of the stack.
@throws EmptyStackException if the stack is empty. */
public T peek();
/** Detects whether this stack is empty.
@return True if the stack is empty. */
public boolean isEmpty();
/** Removes all entries from this stack. */
public void clear();
} // end StackInterface

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/** An interface for the ADT deque.
@author Frank M. Carrano
*/
public interface DequeInterface<T>
{
/** Adds a new entry to the front/back of this deque.
@param newEntry An object to be added. */
public void addToFront(T newEntry);
public void addToBack(T newEntry);
/** Removes and returns the front/back entry of this deque.
@return The object at the front/back of the deque.
@throws EmptyQueueException if the deque is empty before the
operation. */
public T removeFront();
public T removeBack();
/** Retrieves the front/back entry of this deque.
@return The object at the front/back of the deque.
@throws EmptyQueueException if the deque is empty. */
public T getFront();
public T getBack();
/** Detects whether this deque is empty.
@return True if the deque is empty, or false otherwise. */
public boolean isEmpty();
/* Removes all entries from this deque. */
public void clear();
} // end DequeInterface

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/**
A class of runtime exceptions thrown when an attempt is made to access
or remove the front of a queue
@author Hyunryung Kim
*/
public class EmptyQueueException extends RuntimeException
{
public EmptyQueueException()
{
this(null);
} // end default constructor
public EmptyQueueException(String message)
{
super(message);
} // end constructor
} // end EmptyQueueException

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/**
A class that implements a deque of objects by using
a chain of doubly linked nodes.
@author Frank M. Carrano
*/
public final class LinkedDeque<T> implements DequeInterface<T>
{
private DLNode firstNode; // References node at front of queue
private DLNode lastNode; // References node at back of queue
public LinkedDeque()
{
firstNode = null;
lastNode = null;
} // end default constructor
/** Adds a new entry to the front/back of this deque.
@param newEntry An object to be added. */
public void addToFront(T newEntry)
{
DLNode newNode = new DLNode(null, newEntry, firstNode);
if (isEmpty())
lastNode = newNode;
else
firstNode.setPreviousNode(newNode);
firstNode = newNode;
} // end addToFront
public void addToBack(T newEntry)
{
DLNode newNode = new DLNode(lastNode, newEntry, null);
if (isEmpty())
firstNode = newNode;
else
lastNode.setNextNode(newNode);
// end if
lastNode = newNode;
} // end addToBack
/** Removes and returns the front/back entry of this deque.
@return The object at the front/back of the deque.
@throws EmptyQueueException if the deque is empty before the
operation. */
public T removeFront()
{
T front = getFront(); // Might throw an EmptyQueueException
assert firstNode != null;
firstNode = firstNode.getNextNode();
if (firstNode == null)
lastNode = null;
else
firstNode.setPreviousNode(null);
return front;
} // end removeFront
public T removeBack()
{
T back = getBack(); // Might throw an EmptyQueueException
assert lastNode != null;
lastNode = lastNode.getPreviousNode();
if (lastNode == null)
firstNode = null;
else
lastNode.setNextNode(null);
return back;
} // end removeBack
/** Retrieves the front/back entry of this deque.
@return The object at the front/back of the deque.
@throws EmptyQueueException if the deque is empty. */
public T getFront()
{
if (isEmpty())
throw new EmptyQueueException();
else
return firstNode.getData();
} // end getFront
public T getBack()
{
if (isEmpty())
throw new EmptyQueueException();
else
return lastNode.getData();
} // end getBack
/** Detects whether this deque is empty.
@return True if the deque is empty, or false otherwise. */
public boolean isEmpty()
{
return (firstNode == null && lastNode == null);
} // end isEmpty
/* Removes all entries from this deque. */
public void clear()
{
firstNode = null;
lastNode = null;
} // end clear
// @author Frank M. Carrano, Timothy M. Henry
// @version 5.0 */
private class DLNode
{
private T data; // Entry in bag
private DLNode previous; // Link to previous node
private DLNode next; // Link to next node
private DLNode(T dataPortion)
{
this(null, dataPortion, null);
} // end constructor
private DLNode(DLNode previousDLNode, T dataPortion, DLNode nextDLNode)
{
data = dataPortion;
previous = previousDLNode;
next = nextDLNode;
} // end constructor
private T getData()
{
return data;
} // end getData
private void setData(T newData)
{
data = newData;
} // end setData
private DLNode getNextNode()
{
return next;
} // end getNextDLNode
private void setNextNode(DLNode nextDLNode)
{
next = nextDLNode;
} // end setNextDLNode
private DLNode getPreviousNode()
{
return previous;
} // end getPreviousDLNode
private void setPreviousNode(DLNode previousDLNode)
{
previous = previousDLNode;
} // end setPreviousDLNode
} // end DLNode
} // end LinkedQueue

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public class LinkedDequeDemo {
public static void main(String[] args) {
// Create a new LinkedDeque
LinkedDeque<String> deque = new LinkedDeque<>();
System.out.println("=== Testing LinkedDeque Operations ===");
System.out.println("Initial deque is empty: " + deque.isEmpty());
// Add elements to front and back
System.out.println("\nAdding elements to front and back:");
deque.addToFront("Front 1");
deque.addToBack("Back 1");
deque.addToFront("Front 2");
deque.addToBack("Back 2");
// Display front and back
System.out.println("Front element: " + deque.getFront());
System.out.println("Back element: " + deque.getBack());
// Remove elements
System.out.println("\nRemoving elements:");
System.out.println("Removed from front: " + deque.removeFront());
System.out.println("Removed from back: " + deque.removeBack());
// Display again
System.out.println("\nAfter removal:");
System.out.println("Front element: " + deque.getFront());
System.out.println("Back element: " + deque.getBack());
// Test isEmpty
System.out.println("\nDeque is empty: " + deque.isEmpty());
// Clear the deque
System.out.println("\nClearing the deque...");
deque.clear();
System.out.println("Deque is empty after clear: " + deque.isEmpty());
// Test exception handling
System.out.println("\nTesting exception handling:");
try {
System.out.println("Attempting to get front of empty deque...");
System.out.println(deque.getFront());
} catch (EmptyQueueException e) {
System.out.println("Caught EmptyQueueException: " + e.getMessage());
}
try {
System.out.println("Attempting to remove from back of empty deque...");
System.out.println(deque.removeBack());
} catch (EmptyQueueException e) {
System.out.println("Caught EmptyQueueException: " + e.getMessage());
}
}
}