(b) Postcard from Giza (actually: a Pyramid)

It is quite possible that programming to generate rectangles using loops is a piece of cake for you. Here is another programming challenge to see how well you can use the for loop, so now we want you to draw a "Postcard from Giza (Links to an external site.)" i.e. create a view of a famous location: a single side of a hollow pyramid.

You are to write an interactive program that asks the user about a single pyramid's width, a positive integer representing the size of its base and then creates a picture like the one below. Use repetition control structures better known as "loops" to output a hollow pyramid shape based on the width specified by the integer. If the input is an even number, it should be increased to the next odd number.

Don't cheat! Don't use the setw manipulator or output hard-coded strings containing a rigid number of asterisks and spaces – all elements must be created dynamically using loops!

 
    Enter a value to represent the base of a hollow pyramid (not to exceed 80): 11    
     *
    * *
   *   *
  *     *
 *       *
***********

Notice the specific character * (an asterisk) used to generate the hollow pyramid.

When thinking of how to generate a somewhat complex pattern such as the one above using loops we can begin by looking at the pyramid displayed and asking a few questions. Here are a few you might think about.

How is the integer value input of 11 used in this pyramid display? Answer: Used in a loop to generate a line of asterisks for the base of the pyramid.
Can the integer value of 11 be used to determine the number of rows needed to be generated? Answer: A possible formula here might be 11/2+1= 6 rows
How can the integer value of 11 be used to determine the number of outer whitespaces to be generated for each row? Answer: 11/2=5 outer whitespaces for the first row. Determine how to come up with outer whitespaces for the remaining rows as this will be helpful in generating the left slope of the pyramid.
How can the integer value of 11 be used to determine the inner whitespaces to be generated for each row? Answer: Inner whitespace for second row - 11-8 (outer whitespace*2) - 2 (left and right * characters) = 1 whitespace. This sort of study of the pattern progressing through each row will help in generating the right slope of the pyramid.

Remember, there may be multiple ways to complete a programming challenge, and the algorithm here may not necessarily be the only, or even the best, way. Implement the algorithm that you understand and works best for.

Your task is to achieve the following goals:

• ask the user to enter a positive integer value greater than 4 (n) to represent the width or base of the pyramid; This integer value should not be used to represent the rows needed to generate the pyramid, make sure you get this correct. If the input is an even number, it should be increased to the next odd number. The odd number width is needed to ensure that the pyramid has a single tip.

• check the entered value and if it isn't legal, output a message stating the reason;

• draw a hollow pyramid using the character * (an asterisk) with a base of n (see sample output above)

• check to make sure the number of inner whitespaces in each row starting with the second row is an odd number. So for the above sample pyramid with a base of 11, the number of inner whitespaces should be Row2=1, Row3=3, Row4=5 and Row5=7.

• find a reasonable upper limit for the width or base (depending on your screen's dimensions or an acceptable range) and embed it into your input validation code.

• The algorithm should provide the user an opportunity to try the shape generator program again or quit.

Input Validation: Ensure that the user inputs a positive integer value greater than 4 and does not exceed an acceptable range determined by you. Do not accept negative or non-numeric values.

Use meaningful variable names, nested loop statements with proper indentation, appropriate comments, and good prompting messages.

Here us a sample test run of the Postcard from Giza program with some user input validation routines.

Enter a value to represent the base of a hollow pyramid (not to exceed 20): four
OOPS! Looks like you typed some bad data here!
The acceptable base for the pyramid should range from 5 to 20...
Enter a value to represent the base of a hollow pyramid (not to exceed 20): 4
OOPS! Looks like you typed some bad data here!
The acceptable base for the pyramid should range from 5 to 20...
Enter a value to represent the base of a hollow pyramid (not to exceed 20): 11

************** A POSTCARD **************
*********
*********
*********
                   *
                  * *
                 *   *
                *     *
               *       *
              ***********

********** A PYRAMID FROM GIZA ********

Process returned 0 (0x0) execution time : 12.188 s
Press any key to continue.

Note: This is a single file C++ project - No documentation is required on this assignment.

Write a Fraction class whose objects will represent Fractions.

Note: You should not simplify (reduce) fractions, you should not use "const," and all of your code should be in a single file. In this single file, the class declaration will come first, followed by the definitions of the class member functions, followed by the client program.

You must provide the following member functions:

1. A set() operation that takes two integer arguments, a numerator and a denominator, and sets the calling object accordingly.
2. Arithmetic operations that add, subtract, multiply, and divide Fractions. These should be implemented as value returning functions that return a Fraction object. They should be named addedTo, subtract, multipliedBy, and dividedBy. In these functions you will need to declare a local "Fraction" variable, assign to it the result of the mathematical operation, and then return it.
3. A boolean operation named isEqualTo that compares two Fraction objects for equality. Since you aren't reducing your Fractions, you'll need to do this by cross-multiplying. A little review: if numerator1 * denominator2 equals denominator1 * numerator2, then the Fractions are equal.
4. An output operation named print that displays the value of a Fraction object on the screen in the form numerator/denominator.

Your class should have exactly two data members, one to represent the numerator of the Fraction being represented, and one to represent the denominator of the Fraction being represented.

Here's a hint for how you will set up your arithmetic operation functions: You need two Fractions. One is the parameter, one is the calling object. The function multiplies the calling object times the parameter and returns the result. In some ways it is similar to the comesBefore() function from the lesson. That function also needs two Fractions, and one is the calling object and one is the parameter.

When adding or subtracting Fractions, remember that you must first find the common denominator. The easy way to do this is to multiply the denominators together and use that product as the common denominator.

I am providing a client program for you below. You should copy and paste this and use it as your client program. The output that should be produced when the provided client program is run with your class is also given below, so that you can check your results.

I strongly suggest that you design your class incrementally. For example, you should first implement only the set function and the output function, and then test what you have so far. Once this code has been thoroughly debugged, you should add additional member functions, testing each one thoroughly as it is added. You might do this by creating your own client program to test the code at each stage; however, it would probably be better to use the provided client program and comment out code that relates to member functions that you have not yet implemented.

As you can see from the sample output given below, you are not required to reduce Fractions or change improper Fractions into mixed numbers for printing. Just print it as an improper Fraction. You are also not required to deal with negative numbers, either in the numerator or the denominator.

Here is the client program.

#include <iostream>
using namespace std;

int main()
{
    Fraction f1;
    Fraction f2;
    Fraction result;

    f1.set(9, 8);
    f2.set(2, 3);
    
    cout<<"\nArithmetic operations with fraction objects stored in the results class object\n"; 
    cout<<"------------------------------------------------------------------------------\n\n";

    cout << "The product of ";
    f1.print();
    cout << " and ";
    f2.print();
    cout << " is ";
    result = f1.multipliedBy(f2);
    result.print();
    cout << endl;

    cout << "The quotient of ";
    f1.print();
    cout << " and ";
    f2.print();
    cout << " is ";
    result = f1.dividedBy(f2);
    result.print();
    cout << endl;

    cout << "The sum of ";
    f1.print();
    cout << " and ";
    f2.print();
    cout << " is ";
    result = f1.addedTo(f2);
    result.print();
    cout << endl;

    cout << "The difference of ";
    f1.print();
    cout << " and ";
    f2.print();
    cout << " is ";
    result = f1.subtract(f2);
    result.print();
    cout << endl;

    if (f1.isEqualTo(f2)){
        cout << "The two Fractions are equal." << endl;
    } else {
        cout << "The two Fractions are not equal." << endl;
    }
    
    cout<<"\n---------------------------------------------------------\n"; 
    cout<<"\nFraction class implementation test now successfully concluded\n"; 
    // system ("PAUSE"); 
    return 0;
}

This client should produce the output shown here:

C++ CLASS SINGLE-FILE PROJECT Client.cpp - testing a Fraction class implementation 
----------------------------------------------------

Arithmetic operations with Fraction objects stored in the result class object 
------------------------------------------------------------------------------ 
The product of 9/8 and 2/3 is 18/24 
The quotient of 9/8 and 2/3 is 27/16 
The sum of 9/8 and 2/3 is 43/24 
The difference of 9/8 and 2/3 is 11/24 
The two Fractions are not equal. 
--------------------------------------------------------- 
Fraction class implementation test now successfully concluded 

Process returned 0 (0x0) execution time : 10.546 s Press any key to continue.

You may not change the client program in any way. Changing the client program will result in a grade of 0 on the project.

Important notes: Use Console I/O (Scanner and System.out) for all user I/O in this lab.

Do not hard code data file paths or filenames; always ask the user for them.

Complete the Monster Attack project by doing the following: In place of the driver used in homework 2, add a menu with a loop and switch (this is already done, ignore this).

The user must be able to add attacks, get a report on existing attacks, save a file, retrieve a file, and clear the list as many times as she wants in any order she wants.

Replace the array of MonsterAttacks with an ArrayList of MonsterAttacks. This will require changes in several methods. You will need to be able to handle any number of MonsterAttacks the user chooses to input.

Add a method to AttackMonitor that saves the list of attacks to a comma separated values file. Iterate through the list, and for each attack, get each field using the getters from MonsterAttack. Write each value to the file, following each one except the last with a comma. Save the date as a single String in the format MM/DD/YYYY. After you have written out all the data for one attack, write out a newline. Add an item to the main menu that calls this method.

Add a method that clears the list of monster attacks, then uses a Scanner to read data from a .csv file, uses it to instantiate MonsterAttack objects, and adds the attacks to the list. This method must be able to read the files you write out in the method described above. You will need to use String's split() method here. Add an item to the main menu that calls this method. Make sure you can input attack data, save to a file, quit the program, start the program again, read your output file, and show the data from the file.

Below is the original code that needs to be modified to meet the requirements stated above.

MonsterAttack

//side note- the date is incorrect here.. user is supposed to enter the date.. but that shouldn't matter.. still works

import java.util.Date;
class MonsterAttack {
private String monsterName;
private String attackLocation;
private double damagesInMillions;
private Date date;

public MonsterAttack(){
}

public MonsterAttack(String monsterName, String attackLocation, double damagesInMillions, Date date){
this.monsterName = monsterName;
this.attackLocation = attackLocation;
this.damagesInMillions = damagesInMillions;
this.date = date;
}

public String getMonsterName(){
return monsterName;
}
public String getAttackLocation(){
return attackLocation;
}
public double getDamagesInMillions(){
return damagesInMillions;
}
public Date getDate(){
return date;
}
public void setMonsterName(String monsterName){
this.monsterName = monsterName;
}
public void setAttackLocation(String attackLocation){
this.attackLocation = attackLocation;
}
public void setDamagesInMillions(double damagesInMillions){
this.damagesInMillions = damagesInMillions;
}
public void setDate(Date date){
this.date = date;
}
public String toString(){
return " Monster named " + monsterName + " attacked in " + attackLocation + " causing damages of " + damagesInMillions + " dollars in " + date;
}
}

AttackMonitor

import java.util.Scanner;
import java.util.Arrays;
import java.util.Date;

public class AttackMonitor {
Scanner in = new Scanner (System.in);
MonsterAttack[] monsterArray = new MonsterAttack[5];

double[] damagesArray = new double[5];
static double damages = 0;

private void reportAttack(){
for (int i = 0; i < 5; i++){
// if (i == 0)
// System.out.println("press enter");
in.nextLine();
System.out.println("name");
String name = in.nextLine();
System.out.println("location");
String location = in.nextLine();
System.out.println("damage ");
double millions = in.nextDouble();
System.out.println("date");
damagesArray[i] = millions;
Date date = new Date();
damages = damages + millions;
MonsterAttack a = new MonsterAttack(name, location, millions, date);
monsterArray[i] = a;
}
}

private void printAttacks(){
for (int x = 0; x < monsterArray.length; x++){
System.out.println(monsterArray[x]);
}
}

private void showDamages(){
for (int i = 0; i < damagesArray.length; i++){
System.out.println("damage for attack " + (i+1) + ": " + damagesArray[i]);
}
System.out.println("total damages: " + damages);
System.out.println("average damage: " + damages/5);
}

private void findEarliestAttack () {
Date early = monsterArray[0].getDate();
for (int i = 0; i < monsterArray.length; i++){
if (early.compareTo(monsterArray[0].getDate()) > 0){
early = monsterArray[i].getDate();
}
}
System.out.println(early);
}

public void menu(){
String[] choices = { "Quit", "report attacks", "show attacks", "show damages", "find earliest attack"};
int choice;
do {
System.out.println("Enter\n 0 to quit,\n 1 to report attacks, \n 2 to show attacks, \n 3 to show damages, \n 4 to find earliest attack");;
choice = in.nextInt();
switch(choice){
case 0:
break;
case 1:
reportAttack();
break;
case 2:
printAttacks();
break;
case 3:
showDamages();
break;
case 4:
findEarliestAttack();
break;
}
} while (choice !=0);
}
}

MonitorDriver

import java.util.Scanner;
import java.util.Arrays;
import java.util.Date;
public class MonitorDriver{
public static void main (String[] args){
AttackMonitor test = new AttackMonitor();
test.menu();

}
}

This is my current code for a question that asks: "Implement the stack methods push(x) and pop() using two queues". It works well, other than I want it to work for data of type T, not just Int's. (EXCUSE THE INDENTING... CHEGG POSTING DOESNT ALLOW PROPER CODE TO BE UPLOADED... JUST COPY PASTE IT INTO ECLIPSE IDE, HIGHLIGHT ALL CODE, PRESS COMMAND+SHIFT+F AND SHOULD AUTO-FORMAT)

MY QUESTION: How could one modify this code in order to take data of type T, rather than only Int's?

PS: the code must continue to use the data structure provided.... must use the Queue class built... (can't use built-in ArrayList from Java).

HERE IS MY CODE CURRENTLY

//author: Nicolas Wills

package ass1Q1B;

public class StackUsingTwoQueues {

public Queue queue1 = new Queue();

public Queue queue2 = new Queue();

// public int s = queue1.size()+queue2.size(); //dont really use this

// variable... ignore it

public boolean inQueue1 = false; // inQueue1 is true when elements are in queue1. set to false to start means

// first add(x) will add to queue1 first

public void push(int x) { // queue1 holds data when there's an odd number of elements, queue2 holds data

// when even number of elements

if (!inQueue1) { // elements not in queue1, therefore will push to queue1, then transfer queue2

// elements to queue1

queue1.add(x); // add pushed element to previously empty queue1

int queue2StartSize = queue2.size(); // use this variable for "for-loop"... cant put "for(int i=0;

// i

// changes the return value of queue2.size().

for (int i = 0; i < queue2StartSize; i++) {

try {

queue1.add(queue2.remove()); // remove beginning element of queue1, add it to queue2

} catch (NoSuchElementException e) {

}

;

} // end for loop

inQueue1 = true;

} // end else if

else if (inQueue1) { // previous push() added to queue1, therefore add "x" to queue2.

queue2.add(x); // add pushed element to previously empty queue2

int queue1StartSize = queue1.size(); // use this variable for "for-loop"... cant put "for(int i=0;

// i

// change the return value of queue1.size().

for (int i = 0; i < queue1StartSize; i++) {

try {

queue2.add(queue1.remove()); // remove beginning element of queue1, add it to queue2

} catch (NoSuchElementException e) {

}

;

} // end for loop

inQueue1 = false;

} // end else if

}// end push method

// the running time of push O(n+1) time. n for the loop, 1 for the resize()

// operation

public Integer pop() {

Integer x = null; // very sketchy way to get around error

try {

if (inQueue1) {

x = queue1.remove(); // if the elements are currently in queue1, remove first element from queue1

} else {

x = queue2.remove(); // if the elements are currently in queue2, remove first element from queue2

}

} catch (NoSuchElementException e) {

}

;

return x;

}// end pop() method

// the running time of the pop() method is O(1)

public String printArray() {

if (inQueue1) {

return (queue1.stringedArray()); // if the elements are currently in queue1, printArray() will return a

// string version of the contents of queue1

} else

return (queue2.stringedArray()); // if the elements are currently in queue2, printArray() will return a

// string version of the contents of queue2

}

public static void main(String[] args) {

StackUsingTwoQueues myStack = new StackUsingTwoQueues();

// push elements

myStack.push(1);

System.out.println(myStack.printArray());

myStack.push(2);

System.out.println(myStack.printArray());

myStack.push(3);

System.out.println(myStack.printArray());

myStack.push(4);

System.out.println(myStack.printArray());

myStack.push(5);

System.out.println(myStack.printArray());

myStack.push(6);

System.out.println(myStack.printArray());

myStack.push(7);

System.out.println(myStack.printArray());

myStack.push(8);

System.out.println(myStack.printArray());

myStack.push(9);

System.out.println(myStack.printArray());

myStack.push(10);

System.out.println(myStack.printArray());

// pop elements

myStack.pop();

System.out.println(myStack.printArray());

myStack.pop();

System.out.println(myStack.printArray());

myStack.pop();

System.out.println(myStack.printArray());

myStack.pop();

System.out.println(myStack.printArray());

myStack.pop();

System.out.println(myStack.printArray());

myStack.pop();

System.out.println(myStack.printArray());

myStack.pop();

System.out.println(myStack.printArray());

}

}

package ass1Q1B;

//import ass1Q1.illegalOperation;

//import ass1Q1.priorityQ;

public class Queue {

int[] arr = new int[10];

int j=0; // keeps track of index of front of array

int n = 0; //number of elements in array

public int size() {

return n;

}

public boolean add(int x) { // why cant i just return void

if ((n + 1) > arr.length)

resize();

arr[(j + n) % arr.length] = x;

n++;

return true;

}

private void resize() { // only function in queue class that can be private right?

int[] b = new int[(Math.max(1, n * 2))];

for (int k = 0; k < n; k++)

b[k] = arr[(j + k) % arr.length];

arr = b;

j = 0;

}

public int remove() throws NoSuchElementException {

if (n == 0)

throw new NoSuchElementException("cant remove if theres no elements to remove");

int x = arr[j];

j = (j + 1) % arr.length;

n--;

if (arr.length >= 3 * n)

resize();

return x;

}

public String stringedArray() {

String returnString = "";

for(int i=0; i

returnString+= arr[(i+j)%(arr.length)];

}

return returnString;

}

}

Please convert this java program to a program with methods please.

import java.io.*;
import java.util.*;

public class Number{

public static void main(String[] args) {
  
Scanner scan = new Scanner(System.in);

System.out.println("Enter 20 integers ranging from -999 to 999 : "); //print statement

int[] array = new int[20]; //array of size 20

for(int i=0;i<20;i++){

array[i] = scan.nextInt(); //user input

if(array[i]<-999 || array[i]>999){ //check if value is inside the range

System.out.println("Please enter a number between -999 to 999");
i--;
}
}

// Now we have to create 4 array for odd,even,positive,negative number

int odd = 0; //initializing as zero
int even = 0;
int positive = 0;
int negative = 0;

for(int i=0;i<20;i++){

if(array[i]%2 == 0){ //check if even

even++; //increment
}
if(array[i]%2 != 0){ //check if odd

odd++; //increment
}
if(array[i]>0){ //check if positive

positive++; //increment
}   
if(array[i]<0){ //check if negative

negative++; //increment
}
}

//Now initializing array for all

int[] oddA = new int[odd]; //arrays of required size
int[] evenA = new int[even];
int[] positiveA = new int[positive];
int[] negativeA = new int[negative];

int countOdd = 0; //initializing as zero
int countEven = 0; //for array indexing
int countPositive = 0;
int countNegative = 0;

for(int i=0;i<20;i++){

if(array[i]%2 == 0){ //check if even

evenA[countEven] = array[i]; //Putting value
countEven++;
}
if(array[i]%2 != 0){ //check if odd

oddA[countOdd] = array[i]; //Putting value
countOdd++;
}
if(array[i]>0){ //check if positive

positiveA[countPositive] = array[i]; //Putting value
countPositive++;   
}   
if(array[i]<0){ //check if negative

negativeA[countNegative] = array[i]; //Putting value
countNegative++;   
}
}

//Difference between highest and lowest positive number

int highest = -1000; //Initialize
int lowest = 1000;

for(int i=0;i<20;i++){

if(array[i]>0 && array[i]>highest){ //condition for highest positive number

highest = array[i];
}
if(array[i]>0 && array[i]<lowest){ //condition for lowest positve number

lowest = array[i];
}
}

int diff = highest - lowest; //difference

//Sum of all negative numbers

int sumNegative = 0;

for(int i=0;i<negative;i++){

sumNegative = sumNegative + negativeA[i]; //sum of negative number
}

int input = 0;

do{

System.out.println("Enter your choice : ");

System.out.println("1. The orginal array");
System.out.println("2. The array of all odd numbers");
System.out.println("3. The array of all even numbers");
System.out.println("4. The array of all positive numbers");
System.out.println("5. The array of all negative numbers");
System.out.println("6. The highest and lowest postive value and difference between them");
System.out.println("7. The sum of all negative numbers");
System.out.println("8. Display all positive appearing in positive array whose value is less than 50");
System.out.println("9. Display all even numbers in reverse order");
System.out.println("10. Display all multiples of 5 (positive or negative)");

int choice = scan.nextInt(); //user choice

switch(choice){

case 1 :

for(int i=0;i<20;i++){

System.out.print(array[i]+" ");
}
System.out.println("");
break;

case 2 :

for(int i=0;i<odd;i++){

System.out.print(oddA[i]+" ");
}
System.out.println("");
break;

case 3 :

for(int i=0;i<even;i++){

System.out.print(evenA[i]+" ");
}
System.out.println("");
break;

case 4 :

for(int i=0;i<positive;i++){

System.out.print(positiveA[i]+" ");
}
System.out.println("");
break;

case 5 :

for(int i=0;i<negative;i++){

System.out.print(negativeA[i]+" ");
}
System.out.println("");
break;

case 6 :

System.out.println("The highest positive value is : " + highest);
System.out.println("The lowest positive value is : " + lowest);
System.out.println("The difference between the highest and lowest positve value is : " + diff);
break;

case 7 :

System.out.println("The sum of all negative number is : " + sumNegative);
break;

case 8 :

for(int i=0;i<positive;i++){

if(positiveA[i]<50){

System.out.print(positiveA[i]+" ");
}
}
System.out.println("");
break;

case 9 :

for(int i=even-1;i>=0;i--){

System.out.print(evenA[i]+" ");
}
System.out.println("");
break;

case 10 :

for(int i=0;i<20;i++){

if(array[i]%5 == 0){

System.out.print(array[i]+" ");
}
}
System.out.println("");
break;
}

System.out.println("Do you wish to continue : (1 or 0) : Press 1 to continue : ");

input = scan.nextInt();

}while(input == 1);
}
}

Skills needed to complete this assignment: linked lists, stacks.

Postfix notation, is a mathematical notation in which operators follow their operands; for instance, to add 3 and 4, one would write 3 4 + rather than 3 + 4 (infix notation). If there are multiple operations, operators are given immediately after their second operands; so, the expression written 3 − 4 + 5 in conventional notation would be written 3 4 − 5 + in postfix notation: 4 is first subtracted from 3, then 5 is added to it. An advantage of postfix notation is that it removes the need for parentheses that are required by infix notation. While 3 − 4 × 5 can also be written 3 − (4 × 5), which is different from (3 − 4) × 5. In postfix notation, the former could be written 3 4 5 × −, while the latter could be written 3 4 − 5 × or 5 3 4 − ×.

Stacks can be used to evaluate expressions in postfix notations by following these steps: • If a number is typed, push it on the stack. • If an operation is typed, depending on the operation, pop off two numbers from the stack, perform the operation, and push the result back on the stack. You should complete the Stack class and other functions in the template file (found on Carmen) so that when the user enters an expression in postfix notation, the program calculates and shows the result. In this assignment the user enters one-digit positive numbers only, but the result can be any integer. Only basic operations (i.e. +, -, /, *) are entered by the user and integer division is used in calculations. User input ends with a semicolon.

Class Stack uses a linked list to implement a stack, and it has five public member functions:

• Default constructor: initializes the stack to an empty stack • isEmpty: returns true if the stack is empty and false otherwise

• push: pushes a new number to the top of stack

• pop: removes the top of stack

• top: returns the value at the top of stack, does not remove it from stack

You must use the template file and only add you code were you see /*your code here*/. Do not modify other parts of the code. Do not use C/C++ libraries other than iostream and cstdlib.

template code

#include <iostream>
#include <cstdlib>

using namespace std;

const char SENTINEL = ';';

struct Node {
int data;
Node *link;
};

// precondition: c is initialized
// postcondition: returns true if c is '+', '-', '*' or '/'
bool isOperator(char c);

// precondition: o1 and o2 are initialized and op is an operator
// postcondition: returns op(o1, o2), e.g. if op is '-' then returns o1-o2
int calculate(int o1, int o2, char op);

// precondition: c is a digit
// postcondition: returns the integer value of c
int charToInt(char c);

class Stack {

public:
// default constructor
// initializes the stack to an empty stack
Stack();

// this is a const function, meaning it cannot change any of the member variables
// returns true if the stack is empty, false otherwise
bool isEmpty() const;

// this is a const function, meaning it cannot change any of the member variables
// returns the value at the top of stack, does not modify the stack, does not check if the stack is empty or not
int top() const;

// adds data to the top of stack
void push(int data);

// removes the top value of stack, does not return it, does nothing if the stack is empty
void pop();

private:
Node *listHead; // pointer to the head of a linked list

};

int main() {
char in;
Stack operandStack;

cout << "Enter a postfix expression (ending with " << SENTINEL << " and press Enter):\n";
cin >> in ;
while ( in != SENTINEL) {
if (isOperator( in )) {
// pop two numbers from stack
int n1, n2;
if (operandStack.isEmpty()) {
// pring error message
/*your code here*/

exit(1);
}
n2 = operandStack.top();
operandStack.pop();

if (operandStack.isEmpty()) {
// pring error message
/*your code here*/

exit(1);
}
n1 = operandStack.top();
operandStack.pop();

// push the result of calculation to the top of operandStack
/*your code here*/

} else {
// push the number to the top of opernadStack
/*your code here*/

}
cin >> in ;
}

// pop a number from the top of stack
int result;
result = operandStack.top();
operandStack.pop();

if (operandStack.isEmpty()) // nothing left in the stack
cout << "\nThe result is: " << result << endl;
else // there are still numbers in the stack
{
// pring an error message
/*your code here*/

}

return 0;
}

Stack::Stack() {
/*your code here*/
}

bool Stack::isEmpty() const {
/*your code here*/
}

int Stack::top() const {
/*your code here*/
}

void Stack::pop() {
/*your code here*/
}

void Stack::push(int data) {
/*your code here*/
}

int calculate(int o1, int o2, char op) {
/*your code here*/
}

bool isOperator(char c) {
return c == '+' || c == '-' || c == '*' || c == '/';
}

int charToInt(char c) {
return (static_cast<int>(c) - static_cast<int>('0'));}

-The table below details the individual Consumer Price Indices (CPI) for individual expenditure categories for 2016 and 2017:

What was the price change between 2016 and 2017 in the gasoline expenditure category?

1. 216.781%

2. 110.65%

3. 10.65%

4. 195.915%

please explain me how to calculate and answers.

- Read the following excerpt from a U.S. Energy Information Administration Report that was published on January 9, 2018:

Crude Oil Prices. Brent crude oil averaged $54/barrel (b) in 2017, an increase of $10/b from 2016 levels. Prices increased fairly steadily through the second half of the year, with year-end prices higher than the annual average. Daily Brent spot prices ended 2017 near $67/b, which was the highest level since December 2014. The monthly average spot price of Brent crude oil increased by $2/b in December to $64/b, marking only the fourth time that monthly Brent crude oil prices averaged more than $60/b in the past 36 months

Most of the upward price movement in recent months reflects continuing draws in global oil inventory levels. EIA estimates that global petroleum and other liquid fuels inventories fell by an average of 0.4 million b/d in 2017, which was the first year of annual average draws since 2013. In addition, oil prices were supported by OPEC’s November 30, 2017, announcement to extend its crude oil supply reduction agreement through the end of 2018. Also, Brent prices increased in December because of a disruption to the North Sea’s Forties crude oil pipeline system early in the month. The Forties pipeline system is one of the primary distribution networks for Brent crude oil delivery in the North Sea, and its outage curtailed available supply in the near term. Trade press reports indicate the Forties pipeline system restarted operations in late December 2017.

Questions:

Based on the excerpt, was the increase in the gasoline expenditure category CPI due to a change in supply or demand in the market?

1. Demand, because there were several factors affecting the market that were caused by producers of crude oil. In particular, inventory levels increased, OPEC extended production increases, and there was a disruption in a major pipeline system.

2. Supply, because there were several factors affecting the market that were caused by producers of crude oil. In particular, inventory levels declined, OPEC extended production reductions, and there was a disruption in a major pipeline system.

3. Supply because price increases are generally due to production decisions. In addition, supply creates its own demand, thus the supply side of the market will determine equilibrium prices.

4. Demand because as prices rose we saw a reduction in the quantity demanded in the market. This led to the reduction in crude oil inventory levels and the production disruptions.

what is answer?

-Read the following excerpt from a Forbes article that was published on November 3, 2017:

Now department stores’ frantic plunge into the off-price sector is in danger of killing off the full-price apparel business for good, experts warn.

In addition to discounting merchandise in their full-line stores, marked-down goods are increasingly feeding the pipeline in department stores’ ever burgeoning off-price channel, from the already heavily promotional Macy’s expanding its BackstageLinks to an external site. spin-off concept to Nordstrom’s Rack format.“The off-price business is driving growth and getting bigger than the full-price channel,” said Susan LeeLinks to an external site., a partner with consultancy Simon-Kucher.

Today, Nordstrom operates 216 Nordstrom Rack off-price stores, nearly double the number of its 122 full-line stores, just as Saks Fifth Avenue’s 39-store full-line chain is a fraction of its 118-store Off 5th outlet fleet.

The Amazon Factor

Amazon isn’t doing the full-price apparel business any favors either. While fashion brands are by no means flocking to the site, still fearful of losing control of their brand image, the discount-aggressive e-tailer is gunning for apparel, and has scored some big symbolic wins, such as itspartnership with NikeLinks to an external site..

Lord & Taylor department stores, for one, recently started pricing matching AmazonLinks to an external site.. (Not to mention partnering with Wal-Mart in an online mall venture.)

Questions:

Based on the excerpt, was the decrease in the apparel expenditure category CPI due to a change in supply or demand in the market?

1. Supply. This is due to a reduction in overall competition in the low priced apparel market.

2. Supply. This is due to increased competition among suppliers in the apparel market, which reduced prices.

3. Demand because consumers tastes and preferences shifted to higher priced apparel items.

4. Demand. This is due to decreased competition among suppliers in the apparel market, which reduced prices.