Question

Please solve this problem in java.

import java.util.Arrays;

public class PriorityQueue {

/* This class is finished for you.
*/
private static class Customer implements Comparable {
private double donation;

public Customer(double donation) {
this.donation = donation;
}

public double getDonation() {
return donation;
}

public void donate(double amount) {
donation += amount;
}

public int compareTo(Customer other) {
double diff = donation - other.donation;
if (diff < 0) {
return -1;
} else if (diff > 0) {
return 1;
} else {
return 0;
}
}

public String toString() {
return String.format("$%.2f", donation);
}
}

private Customer[] data;
private int size;

public PriorityQueue(int capacity) {
data = new Customer[capacity];
size = 0;
}
  
public PriorityQueue() {
this(10);
}

/* Add a customer to the queue.
* Remember to do so in a way that keeps the queue in sorted order!
*/
public void push(Customer customer) {

}

/* Remove and return the highest priority customer from the queue.
*/
public Customer pop() {
return null;
}

/* Return, but don't remove, the highest priority item from the queue.
*/
public Customer peek() {
return null;
}

/* Given the index of a customer, increase their donation amount, letting
* them cut in line if necessary.
*
* Refer to the Customer class to remind yourself the operations you can do
* on a customer.
*/
public void bump(int customerIndex, double amount) {
  
}

public String toString() {
return Arrays.toString(data);
}

public static void main(String[] args) {
PriorityQueue line = new PriorityQueue(6);
  
line.push(new Customer(5.00));
line.push(new Customer(10.00));
line.push(new Customer(1.00));

System.out.println(line.pop());
System.out.println(line.pop());

line.push(new Customer(20.00));
line.push(new Customer(15.00));
line.push(new Customer(2.00));

line.bump(1, 30.00);
line.bump(3, 60.00);
System.out.println(line.pop());
System.out.println(line.peek());
System.out.println(line.pop());
System.out.println(line.pop());
System.out.println(line.pop());
}
}

RESULT

$10.00
$5.00
$61.00
$45.00
$45.00
$20.00
$2.00

Answer 1

import java.util.Arrays;

public class PriorityQueue {

/* This class is finished for you.
*/
private static class Customer implements Comparable<Customer> {
private double donation;

public Customer(double donation) {
this.donation = donation;
}

public double getDonation() {
return donation;
}

public void donate(double amount) {
donation += amount;
}

public int compareTo(Customer other) {
double diff = donation - other.donation;
if (diff < 0) {
return -1;
} else if (diff > 0) {
return 1;
} else {
return 0;
}
}

// If following changes can be made in compareTo() function then reversing of an array is not required

// public int compareTo(Customer other) {
// double diff = donation - other.donation;
// if (diff < 0) {
// return 1;
// } else if (diff > 0) {
// return -1;
// } else {
// return 0;
// }
// }

public String toString() {
return String.format("$%.2f", donation);
}
}

private Customer[] data;
private int size;

public PriorityQueue (int capacity) {
data = new Customer[capacity];
size = 0;
}
  
public PriorityQueue () {
this(10);
}
public void push(Customer customer) {

// Pushed data in queue and sorted the queue
data[size]=customer;

// After pushing each element the size is increased
size++;

// Arrays sorted in ascending order due to the given compareTo() function and
// so the array is reversed   
Arrays.sort(data,0,size);
int i; Customer t;
for (i = 0; i < size / 2; i++) {
t = data[i];
data[i] = data[size - i - 1];
data[size - i - 1] = t;
}
}

public Customer pop() {
  

Customer cust=data[0];

// Shifting all the elements after popping the top element and decreasing the size
for(int i=0;i<size-1;i++)
data[i]=data[i+1];
size--;
return cust;

}

public Customer peek() {
return data[0];
}

public void bump(int customerIndex, double amount) {

// Called function donate in customer class to further
// add the amount

data[customerIndex].donate(amount);

// Now the value has changed of an element hence, may not be sorted
// So sorted again and then reversed

Arrays.sort(data,0,size);
int i; Customer t;
for (i = 0; i < size / 2; i++) {
t = data[i];
data[i] = data[size - i - 1];
data[size - i - 1] = t;
}
}

public String toString() {
return Arrays.toString(data);
}

public static void main(String[] args) {
PriorityQueue line = new PriorityQueue (6);
  
line.push(new Customer(5.00));
line.push(new Customer(10.00));
line.push(new Customer(1.00));

System.out.println(line.pop());
System.out.println(line.pop());

line.push(new Customer(20.00));
line.push(new Customer(15.00));
line.push(new Customer(2.00));

line.bump(1, 30.00);
line.bump(3, 60.00);
System.out.println(line.pop());
System.out.println(line.peek());
System.out.println(line.pop());
System.out.println(line.pop());
System.out.println(line.pop());
}
}