Question

This is what I have so far. I have to create an insert and delete method for the heap.

public class HeapClass<E> {

private int size;

private E [] heap;

public HeapClass(){

this.heap = (E[]) new Object[10];

}

public HeapClass(E root) {

this.heap = (E[]) new Object[10];

this.heap[0] = root;

}

public HeapClass(E[] heap) {

this.heap = heap;

}

Answer 1

public class HeapClass <E extends Comparable<E>>{
private static final int CAPACITY = 2;
private int size;
private E[] heap;
  
public HeapClass()
{
this.size = 0;
this.heap = (E[]) new Comparable[CAPACITY];
}
  
public HeapClass(E[] heap)
{
this.size = heap.length;
this.heap = (E[]) new Comparable[heap.length+1];
}
  
public HeapClass(E root)
{
this.heap = (E[]) new Comparable[10];
this.heap[0] = root;
}
  
private void doubleSize()
{
E [] old = this.heap;
this.heap = (E []) new Comparable[this.heap.length * 2];
System.arraycopy(old, 1, this.heap, 1, this.size);
}
  
public void insert(E x)
{
if(this.size == this.heap.length - 1) doubleSize();

//Insert a new item to the end of the array
int pos = ++this.size;

//Percolate up
for(; pos > 1 && x.compareTo(this.heap[pos/2]) < 0; pos = pos/2 )
this.heap[pos] = this.heap[pos/2];

this.heap[pos] = x;
}
  
private void percolatingDown(int k)
{
E tmp = this.heap[k];
int child;

for(; 2*k <= this.size; k = child)
{
child = 2*k;

if(child != this.size && this.heap[child].compareTo(this.heap[child + 1]) > 0) child++;

if(tmp.compareTo(this.heap[child]) > 0)
this.heap[k] = this.heap[child];
else
break;
}
this.heap[k] = tmp;
}
  
public E deleteFromTop() throws RuntimeException
{
if (size == 0) throw new RuntimeException();
E min = heap[1];
heap[1] = heap[size--];
percolatingDown(1);
return min;
}
  
public void printHeap()
{
System.out.print("Heap: ");
for(int i = 0; i < this.heap.length; i++)
{
if(this.heap[i] != null)
{
System.out.print(this.heap[i] + " ");
}
}
System.out.println();
}
  
public static void main(String[]args)
{
HeapClass<String> heap = new HeapClass<>();
heap.insert("c");
heap.insert("h");
heap.insert("e");
heap.insert("g");
heap.insert("g");
heap.insert("i");
heap.insert("n");
heap.insert("g");
heap.printHeap();
  
heap.deleteFromTop();
heap.printHeap();
}
}

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