CS代考程序代写 Java algorithm package edu.iastate.cs311.hw2;

package edu.iastate.cs311.hw2;

/**
* @author
* A simple priority queue interface and a class template implementing
* the interface with a heap and a heap sort algorithm. This code template is
* written by Xiaoqiu Huang for Com S 311 in Spring 2021.
*/

import java.util.List;
import java.util.ArrayList;
import java.util.NoSuchElementException;

interface ExtendedPriorityQueue
{
int size();
boolean isEmpty();
void add(E element);

// Returns a high-priority element without removing it.
E getMin();

// Removes a high-priority element.
E removeMin();

// Returns an element at the last nonleaf node in the heap
E getLastInternal();

// Removes all elements at each leaf node in the heap
void trimEveryLeaf();

// Shows the heap as a binary tree in plain text
void showHeap();
}

public class Heap>
implements ExtendedPriorityQueue
{
private static final int INIT_CAP = 10; // A default size of list
private ArrayList list; // used as an array to keep the elements in the heap
// list.size() returns the number of elements in the list,
// which is also the size of the heap.
// For 0 <= k < list.size(), list.get(k) returns the element at position k of list // list.remove( list.size() - 1 ) removes the last element from the list; // note that there is no need to remove any element before the last element. public Heap() { list = new ArrayList(INIT_CAP);
}

public Heap(int aSize)
{
if ( aSize < 1 ) throw new IllegalStateException(); list = new ArrayList(aSize);
}

// Builds a heap from a list of elements.
public Heap(List aList)
{
int j, k;
int len = aList.size();
if ( len < 1 ) throw new IllegalArgumentException(); list = new ArrayList(len);
for ( E t : aList )
list.add(t);
if ( len < 2 ) return; j = (len - 2) / 2; // j is the largest index of an internal node with a child. for ( k = j; k >= 0; k– )
percolateDown(k);
} // O(n) time

public int size()
{
return list.size();
}

public boolean isEmpty()
{
return list.isEmpty();
}

public void add(E element)
{
if ( element == null )
throw new NullPointerException(“add”);
list.add(element); // append it to the end of the list
percolateUp(); // move it up to the proper place
}

// TODO: O(log n)
// Moves the last element up to the proper place so that the heap property holds.
private void percolateUp()
{
}

// Swaps the elements at the parent and child indexes.
private void swap(int parent, int child)
{
E tmp = list.get(parent);
list.set( parent, list.get(child) );
list.set(child, tmp);
}

public E getMin()
{
if ( list.isEmpty() )
throw new NoSuchElementException();
return list.get(0);
}

// TODO: O(1)
// Returns an element at the last nonleaf node in the heap
// If the size of the heap is less than 2, it throws new NoSuchElementException().
public E getLastInternal()
{
}

public E removeMin()
{
if ( list.isEmpty() )
throw new NoSuchElementException();
E minElem = list.get(0); // get the min element at the root
list.set(0, list.get(list.size() – 1) ); // copy the last element to the root
list.remove( list.size() – 1 ); // remove the last element from the list
if ( ! list.isEmpty() )
percolateDown(0); // move the element at the root down to the proper place
return minElem;
}

// TODO: O(n)
// If the heap contains internal (nonleaf) nodes, trim every leaf element.
// If the size of the heap is less than 2, it throws new NoSuchElementException().
public void trimEveryLeaf()
{
}

// TODO: O(log n)
// Move the element at index start down to the proper place so that the heap property holds.
private void percolateDown(int start)
{
if ( start < 0 || start >= list.size() )
throw new RuntimeException(“start < 0 or >= n”);
}

// Shows the tree used to implement the heap with the root element at the leftmost column
// and with ‘null’ indicating no left or right child.
// This method is used to help check if the heap is correctly constructed.
public void showHeap()
{
if ( list.isEmpty() ) return;
recShowHeap(0, “>”);
}

public void recShowHeap(Integer r, String level)
{
int len = list.size();
if ( r >= len )
{
System.out.println(level + “null”);
return;
}
System.out.println(level + list.get(r) ); // get the min element at the root
recShowHeap(2 * r + 1, ” ” + level);
recShowHeap(2 * r + 2, ” ” + level);
}

// This method repeatedly removes the smallest element in the heap and add it to the list.
public static > void heapSort(List aList)
{
if ( aList.isEmpty() ) return;
Heap aHeap = new Heap(aList);
aList.clear();
while ( ! aHeap.isEmpty() )
aList.add( aHeap.removeMin() );
}
} // Heap