JavaDataStructures/Heap/HeapModule.java at master · benaich/JavaDataStructures · GitHub

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package Heap;

public class HeapModule {

public static interface Heap<T> {

Heap left();

Heap right();

T data();

int rank();

boolean isEmpty();

int size();

@Override

String toString();

}

public static class NonEmptyHeap<T> implements Heap<T> {

public Heap left;

public Heap right;

public T data;

public int rank;

public NonEmptyHeap(T x, Heap a, Heap b) {

this(0, x, a, b);

}

public NonEmptyHeap(int r, T x, Heap a, Heap b) {

rank = r;

data = x;

left = a;

right = b;

}

@Override

public Heap left() {

return left;

}

@Override

public Heap right() {

return right;

}

@Override

public T data() {

return data;

}

@Override

public int rank() {

return rank;

}

@Override

public boolean isEmpty() {

return false;

}

@Override

public int size(){

return 1 + left.size() + right.size();

}

public static final Heap<? extends Object> EMPTY = new Heap<Object>() {

@Override

public Heap left() {

throw new UnsupportedOperationException();

}

@Override

public Heap right() {

throw new UnsupportedOperationException();

}

@Override

public Object data() {

throw new UnsupportedOperationException();

}

@Override

public int rank() {

return 0;

}

@Override

public String toString() {

return "";

}

@Override

public boolean isEmpty() {

return true;

}

@Override

public int size(){

return 0;

}

};

/* retourn EMPTY instnace (singleton pattern) */

public static <T> Heap<T> emptyHeap() {

return (Heap) EMPTY;

}

/* build a heap v1 */

public static <T extends Comparable<? super T>> Heap<T> heap(T x, Heap<T> a, Heap<T> b) {

if (a.rank() > b.rank()) {

return new NonEmptyHeap<>(b.rank() + 1, x, a, b);

}

return new NonEmptyHeap<>(a.rank() + 1, x, b, a);

}

/* build a heap v2 */

public static <T extends Comparable<? super T>> Heap<T> heap(T x) {

return heap(x, emptyHeap(), emptyHeap());

}

/* insert an element into a heap */

public static <T extends Comparable<? super T>> Heap<T> insert(Heap<T> a, T x) {

if (a.isEmpty()) {

return heap(x);

}

if (a.data().compareTo(x) <= 0) {

return heap(a.data(), a.left(), insert(a.right(), x));

} else {

return heap(x, a.left(), insert(a.right(), a.data()));

}

/* create a balanced heap from an array */

public static <T extends Comparable<? super T>> Heap<T> insert(T... array) {

Heap<T> root = emptyHeap();

for (T item : array) {

root = insert(root, item);

}

return root;

}

/* merge two balanced heaps into one balanced heap*/

public static <T extends Comparable<? super T>> Heap<T> merge(Heap<T> a, Heap<T> b) {

if (a.isEmpty()) {

return b;

}

if (b.isEmpty()) {

return a;

}

if (a.data().compareTo(b.data()) <= 0) {

return heap(a.data(), b, merge(a.left(), a.right()));

}

return heap(b.data(), merge(a.data(), b.left(), b.right()), merge(a.left(), a.right()));

}

/* merge a key + two balanced heaps into one balanced heap*/

public static <T extends Comparable<? super T>> Heap<T> merge(T x, Heap<T> a, Heap<T> b) {

if (a.isEmpty()) {

return insert(a, x);

}

if (b.isEmpty()) {

return insert(b, x);

}

if ((x.compareTo(a.data()) <= 0) && (x.compareTo(b.data()) <= 0)) {

return heap(x, a, b);

}

if (a.data().compareTo(b.data()) <= 0) {

return heap(a.data(), merge(x, a.left(), a.right()), b);

}

return heap(b.data(), merge(x, b.left(), b.right()), a);

}

/* return the minimum key of a heap */

public static <T extends Comparable<? super T>> T min(Heap<T> root) {

if (root == null) {

return null;

}

return root.data();

}

/* remove the minimum key of a heap */

public static <T extends Comparable<? super T>> Heap<T> delete(Heap<T> root) {

if (root == null) {

return null;

}

return merge(root.left(), root.right());

}

/* print heap element */

public static <T> void printNice(Heap<T> root, int level) {

if (root.isEmpty()) {

return;

}

printNice(root.right(), level + 1);

if (level != 0) {

for (int i = 0; i < level - 1; i++) {

System.out.print("| ");

}

System.out.println("|---" + root.data());

} else {

System.out.println(root.data());

}

printNice(root.left(), level + 1);

}

public static void main(String[] args) {

Heap<Integer> heap1 = insert(5, 9, 3);

System.out.println("------------ Balanced Heap 1 ------------");

printNice(heap1, 1);

Heap<Integer> heap3 = insert(1, 8, 2);

System.out.println("------------ Balanced Heap 2 ------------");

printNice(heap3, 1);

System.out.println("------------ Merge Heap 1 & Heap 2 ------------");

printNice(merge(heap1, heap3), 1);

}

JavaDataStructures/Heap/HeapModule.java at master · benaich/JavaDataStructures · GitHub

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