Question

Write a program in Java to implement the max-priority queue using max-heap data structure. Implement the max-heap data structure using an integer array of 10 cells. (Do not use Java in-built PriorityQueue class.) [In a max-heap, the root node and the intermediate node vales are always greater than their children.] First, take 10 integer values from the user and insert them in the max-priority queue. Then print the elements of the queue. After that, delete two elements from the queue and print them. You can use Java Scanner class to take inputs from the user. The sample inputs/ outputs are given below:
Sample inputs and outputs:
(User’s inputs are shown in bold)
Enter 10 values: 5 15 9 7 20 18 8 6 1 11
The elements of the max-priority queue: 20 15 18 6 11 9 8 5 1 7
The element removed after first deletion: 20
The element removed after second deletion: 18

Answer 1

import java.util.*;
class solve{

static int []H = new int[10];
static int size = -1;

static int parent(int i)
{
return (i - 1) / 2;
}

static int leftChild(int i)
{
return ((2 * i) + 1);
}

static int rightChild(int i)
{
return ((2 * i) + 2);
}

static void shiftUp(int i)
{
while (i > 0 &&
H[parent(i)] < H[i])
{
  
swap(parent(i), i);

i = parent(i);
}
}

static void shiftDown(int i)
{
int maxIndex = i;

int l = leftChild(i);

if (l <= size &&
H[l] > H[maxIndex])
{
maxIndex = l;
}

int r = rightChild(i);

if (r <= size &&
H[r] > H[maxIndex])
{
maxIndex = r;
}

if (i != maxIndex)
{
swap(i, maxIndex);
shiftDown(maxIndex);
}
}

static void insert(int p)
{
size = size + 1;
H[size] = p;

shiftUp(size);
}

static int extractMax()
{
int result = H[0];

H[0] = H[size];
size = size - 1;
shiftDown(0);
return result;
}

static int getMax()
{
return H[0];
}

static void remove(int i)
{
H[i] = getMax() + 1;
shiftUp(i);
extractMax();
}

static void swap(int i, int j)
{
int temp= H[i];
H[i] = H[j];
H[j] = temp;
}

public static void main(String[] args)
{

System.out.println("Enter 10 values:")

Scanner sc = new Scanner(System.in);
for(int r =0 ; r < 10 ;r++)
{
int e= sc.nextInt();
insert (e);
}

int i = 0;

System.out.print("Element in the priority Queue : ");
while (i <= size)
{
System.out.print(H[i] + " ");
i++;
}

System.out.print("\n");

remove(0);
System.out.print("Priority queue after " +
"removing the first Element: ");
int l = 0;
while (l <= size)
{
System.out.print(H[l] + " ");
l++;
}

remove(0);
System.out.print("Priority queue after " +
"removing the second Element: ");
int l = 0;
while (l <= size)
{
System.out.print(H[l] + " ");
l++;
}

}
}