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A4: Implementierung Heap 

~ iterativ fertig
This commit is contained in:
Johannes Theiner 2018-12-09 19:40:58 +01:00
parent 3d0bd7a924
commit fdc84e3876
4 changed files with 167 additions and 21 deletions
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algodat.iml
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src/main/java/xyz/joethei/studium/algodat/praktikum/blatt4/Heap.java Normal file
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package xyz.joethei.studium.algodat.praktikum.blatt4;
import java.util.Arrays;
public class Heap<E extends Comparable<E>> {
private Object[] array;
private int last = 0;
private int capacity;
private int swapCount = 0;
public Heap(int capacity) {
array = new Object[capacity + 1];
this.capacity = capacity;
}
public Heap(Object[] array) {
this.capacity = array.length + 1;
this.array = array;
this.last = array.length-1;
down();
}
public int size() {
return last;
}
public boolean isEmpty() {
return size() == 0;
}
public int getSwapCount() {
return swapCount;
}
public E min() throws RuntimeException {
if (isEmpty())
throw new RuntimeException("The heap is empty.");
else
return (E) array[1];
}
private int compare(Object x, Object y) {
return ((E) x).compareTo((E) y);
}
public void insert(E e) throws RuntimeException {
if (size() == capacity)
throw new RuntimeException("Heap overflow.");
else {
last++;
array[last] = e;
up();
}
}
public E removeMin() throws RuntimeException {
if (isEmpty())
throw new RuntimeException("Heap is empty.");
else {
E min = min();
array[1] = array[last];
last--;
down();
return min;
}
}
private void down() {
int index = 1;
while (true) {
int child = index * 2;
if (child > size())
break;
if (child + 1 <= size()) {
child = findMin(child, child + 1);
}
if (compare(array[index], array[child]) <= 0)
break;
swap(index, child);
index = child;
}
}
private void up() {
int index = size();
while (index > 1) {
int parent = index / 2;
if (compare(array[index], array[parent]) >= 0)
break;
swap(index, parent);
index = parent;
}
}
private void swap(int i, int j) {
swapCount++;
Object temp = array[i];
array[i] = array[j];
array[j] = temp;
}
private int findMin(int leftChild, int rightChild) {
if (compare(array[leftChild], array[rightChild]) <= 0)
return leftChild;
else
return rightChild;
}
public String toString() {
return Arrays.toString(array);
}
}

34
src/main/java/xyz/joethei/studium/algodat/praktikum/blatt4/HeapMain.java Normal file
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package xyz.joethei.studium.algodat.praktikum.blatt4;
public class HeapMain {
public static void main(String[] args) {
int[] n = new int[]{1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767, 65535};
System.out.println("iterativ");
for(int i : n) {
Heap heap = getHeap(i);
System.out.println(i + " : " + heap.getSwapCount());
}
System.out.println("geblockt");
for(int i : n) {
Integer[] array = new Integer[i];
for (int j = i; j > 0; j--) {
array[j-1] = j;
}
Heap heap = new Heap(array);
System.out.println(i + " : " + heap.getSwapCount());
}
}
public static Heap getHeap(int n) {
Heap<Integer> heap = new Heap<>(n);
for (int i = n; i > 0; i--) {
heap.insert(i);
}
return heap;
}
}

18
src/test/java/xyz/joethei/studium/algodat/praktikum/HeapTest.java Normal file
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package xyz.joethei.studium.algodat.praktikum;
import org.junit.jupiter.api.Test;
import xyz.joethei.studium.algodat.praktikum.blatt4.HeapMain;
import static org.junit.jupiter.api.Assertions.assertEquals;
class HeapTest {
@Test
void iterativ() {
int[] n = new int[]{1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767, 65535};
int[] res = new int[]{0, 2, 10, 34, 98, 258, 642, 1538, 3586, 8194, 18434, 40962, 90114, 196610, 425986, 917506};
for (int i = 0; i < 15; i++) {
assertEquals(HeapMain.getHeap(n[i]).getSwapCount(), res[i]);
}
}
}