BinaryHeap Java实现

public class BinaryHeap<AnyType extends Comparable<? super AnyType>> {

private static final int DEFAULT_CAPACITY = 10;
    private AnyType[] array;
    private int currentSize;

public BinaryHeap() {

this(DEFAULT_CAPACITY);
    }

public BinaryHeap(int capacity) {
        currentSize = 0;
        array = (AnyType[]) new Comparable[capacity];

}

public BinaryHeap(AnyType[] items) {
        currentSize = items.length;

array = (AnyType[]) new Comparable[(array.length + 2) * 11 / 10];

int i = 0;
        for (AnyType item : items) {
            array[i++] = item;
            buildHeap();
        }

}

public void makeEmpty() {
        currentSize = 0;
    }

public boolean isEmpty() {
        return currentSize == 0;
    }

public AnyType findMin() {
        if (isEmpty())
            System.out.println("this is empty");
        return array[1];
    }
     private void enlargeArray( int newSize )
        {
            AnyType [] old = array;
            array = (AnyType []) new Comparable[ newSize ];
            for( int i = 0; i < old.length; i++ )
                array[ i ] = old[ i ];        
        }
     public void insert( AnyType x )
        {
            if( currentSize == array.length - 1 )
                enlargeArray( array.length * 2 + 1 );

// Percolate up
            int hole = ++currentSize;
            for( ; hole > 1 && x.compareTo( array[ hole / 2 ] ) < 0; hole /= 2 )
                array[ hole ] = array[ hole / 2 ];
            array[ hole ] = x;
        }

public AnyType deleteMin() {
        if (isEmpty())
            System.out.println("this is empty");

AnyType minItem = findMin();
        array[1] = array[currentSize--];
        percolateDown(1);

return minItem;
    }

private void buildHeap() {
        for (int i = currentSize / 2; i > 0; i--)
            percolateDown(i);
    }

private void percolateDown(int hole) {

int child;
        AnyType tmp = array[hole];
        for (; hole * 2 < currentSize; hole = child) {

child = hole * 2;
            if (child != currentSize
                    && array[child + 1].compareTo(array[child]) < 0) {
                child++;
            }
            if (array[child].compareTo(tmp) < 0)
                array[hole] = array[child];
            else
                break;
        }
        array[hole] = tmp;
    }

public static void main( String [ ] args )
        {
            int numItems = 10000;
            BinaryHeap<Integer> h = new BinaryHeap<Integer>( );
            int i = 37;

for( i = 37; i != 0; i = ( i + 37 ) % numItems )
                h.insert( i );
            for( i = 1; i < numItems; i++ )
                if( h.deleteMin( ) != i )
                    System.out.println( "Oops! " + i );
        }
    
    
}