文章图片标题

红黑树 Java 代码

分类:算法与数据结构 作者:阳光倾城 评论:0 点击: 442 次 日期:2016-08-01


红黑树 Java 代码

// RedBlackTree class
//
// CONSTRUCTION: with a negative infinity sentinel
//
// ******************PUBLIC OPERATIONS*********************
// void insert( x )       --> Insert x
// void remove( x )       --> Remove x (unimplemented)
// Comparable find( x )   --> Return item that matches x
// Comparable findMin( )  --> Return smallest item
// Comparable findMax( )  --> Return largest item
// boolean isEmpty( )     --> Return true if empty; else false
// void makeEmpty( )      --> Remove all items
// void printTree( )      --> Print all items
// ******************ERRORS********************************
// Exceptions are thrown by insert if warranted and remove.
/**
* Implements a red-black tree.
* Note that all "matching" is based on the compareTo method.
* @author Mark Allen Weiss
*/
public class RedBlackTree {
    /**
     * Construct the tree.
     */
    public RedBlackTree( ) {
        header      = new RedBlackNode( null );
        header.left = header.right = nullNode;
    }
    /**
     * Compare item and t.element, using compareTo, with
     * caveat that if t is header, then item is always larger.
     * This routine is called if is possible that t is header.
     * If it is not possible for t to be header, use compareTo directly.
     */
    private final int compare( Comparable item, RedBlackNode t ) {
        if( t == header )
            return 1;
        else
            return item.compareTo( t.element );
    }
    /**
     * Insert into the tree.
     * @param item the item to insert.
     * @throws DuplicateItemException if item is already present.
     */
    public void insert( Comparable item ) {
        current = parent = grand = header;
        nullNode.element = item;
        while( compare( item, current ) != 0 ) {
            great = grand; grand = parent; parent = current;
            current = compare( item, current ) < 0 ?
                current.left : current.right;
            // Check if two red children; fix if so
            if( current.left.color == RED && current.right.color == RED )
                handleReorient( item );
        }
        // Insertion fails if already present
        if( current != nullNode )
            throw new DuplicateItemException( item.toString( ) );
        current = new RedBlackNode( item, nullNode, nullNode );
        // Attach to parent
        if( compare( item, parent ) < 0 )
            parent.left = current;
        else
            parent.right = current;
        handleReorient( item );
    }
    /**
     * Remove from the tree.
     * @param x the item to remove.
     * @throws UnsupportedOperationException if called.
     */
    public void remove( Comparable x ) {
        throw new UnsupportedOperationException( );
    }
    /**
     * Find the smallest item  the tree.
     * @return the smallest item or null if empty.
     */
    public Comparable findMin( ) {
        if( isEmpty( ) )
            return null;
        RedBlackNode itr = header.right;
        while( itr.left != nullNode )
            itr = itr.left;
        return itr.element;
    }
    /**
     * Find the largest item in the tree.
     * @return the largest item or null if empty.
     */
    public Comparable findMax( ) {
        if( isEmpty( ) )
            return null;
        RedBlackNode itr = header.right;
        while( itr.right != nullNode )
            itr = itr.right;
        return itr.element;
    }
    /**
     * Find an item in the tree.
     * @param x the item to search for.
     * @return the matching item or null if not found.
     */
    public Comparable find( Comparable x ) {
        nullNode.element = x;
        current = header.right;
        for( ; ; ) {
            if( x.compareTo( current.element ) < 0 )
                current = current.left;
            else if( x.compareTo( current.element ) > 0 )
                current = current.right;
            else if( current != nullNode )
                return current.element;
            else
                return null;
        }
    }
    /**
     * Make the tree logically empty.
     */
    public void makeEmpty( ) {
        header.right = nullNode;
    }
    /**
     * Print all items.
     */
    public void printTree( ) {
        printTree( header.right );
    }
    /**
     * Internal method to print a subtree in sorted order.
     * @param t the node that roots the tree.
     */
    private void printTree( RedBlackNode t ) {
        if( t != nullNode ) {
            printTree( t.left );
            System.out.println( t.element );
            printTree( t.right );
        }
    }
    /**
     * Test if the tree is logically empty.
     * @return true if empty, false otherwise.
     */
    public boolean isEmpty( ) {
        return header.right == nullNode;
    }
    /**
     * Internal routine that is called during an insertion
     * if a node has two red children. Performs flip and rotations.
     * @param item the item being inserted.
     */
    private void handleReorient( Comparable item ) {
        // Do the color flip
        current.color = RED;
        current.left.color = BLACK;
        current.right.color = BLACK;
        if( parent.color == RED )   // Have to rotate
        {
            grand.color = RED;
            if( ( compare( item, grand ) < 0 ) !=
                    ( compare( item, parent ) < 0 ) )
                parent = rotate( item, grand );  // Start dbl rotate
            current = rotate( item, great );
            current.color = BLACK;
        }
        header.right.color = BLACK; // Make root black
    }
    /**
     * Internal routine that performs a single or double rotation.
     * Because the result is attached to the parent, there are four cases.
     * Called by handleReorient.
     * @param item the item in handleReorient.
     * @param parent the parent of the root of the rotated subtree.
     * @return the root of the rotated subtree.
     */
    private RedBlackNode rotate( Comparable item, RedBlackNode parent ) {
        if( compare( item, parent ) < 0 )
            return parent.left = compare( item, parent.left ) < 0 ?
                rotateWithLeftChild( parent.left )  :  // LL
                rotateWithRightChild( parent.left ) ;  // LR
        else
            return parent.right = compare( item, parent.right ) < 0 ?
                rotateWithLeftChild( parent.right ) :  // RL
                rotateWithRightChild( parent.right );  // RR
    }
    /**
     * Rotate binary tree node with left child.
     */
    private static RedBlackNode rotateWithLeftChild( RedBlackNode k2 ) {
        RedBlackNode k1 = k2.left;
        k2.left = k1.right;
        k1.right = k2;
        return k1;
    }
    /**
     * Rotate binary tree node with right child.
     */
    private static RedBlackNode rotateWithRightChild( RedBlackNode k1 ) {
        RedBlackNode k2 = k1.right;
        k1.right = k2.left;
        k2.left = k1;
        return k2;
    }
    private static class RedBlackNode {
        // Constructors
        RedBlackNode( Comparable theElement ) {
            this( theElement, null, null );
        }
        RedBlackNode( Comparable theElement, RedBlackNode lt, RedBlackNode rt ) {
            element  = theElement;
            left     = lt;
            right    = rt;
            color    = RedBlackTree.BLACK;
        }
        Comparable   element;    // The data in the node
        RedBlackNode left;       // Left child
        RedBlackNode right;      // Right child
        int          color;      // Color
    }
    private RedBlackNode header;
    private static RedBlackNode nullNode;
    static         // Static initializer for nullNode
    {
        nullNode = new RedBlackNode( null );
        nullNode.left = nullNode.right = nullNode;
    }
    private static final int BLACK = 1;    // Black must be 1
    private static final int RED   = 0;
    // Used in insert routine and its helpers
    private static RedBlackNode current;
    private static RedBlackNode parent;
    private static RedBlackNode grand;
    private static RedBlackNode great;
    // Test program
    public static void main( String [ ] args ) {
        RedBlackTree t = new RedBlackTree( );
        final int NUMS = 400000;
        final int GAP  =  35461;
        System.out.println( "Checking... (no more output means success)" );
        for( int i = GAP; i != 0; i = ( i + GAP ) % NUMS )
            t.insert( new Integer( i ) );
        if( ((Integer)(t.findMin( ))).intValue( ) != 1 ||
                ((Integer)(t.findMax( ))).intValue( ) != NUMS - 1 )
            System.out.println( "FindMin or FindMax error!" );
        for( int i = 1; i < NUMS; i++ )
            if( ((Integer)(t.find( new Integer( i ) ))).intValue( ) != i )
                System.out.println( "Find error1!" );
    }
}
/**
* Exception class for duplicate item errors
* in search tree insertions.
* @author Mark Allen Weiss
*/
public class DuplicateItemException extends RuntimeException
{
    /**
     * Construct this exception object.
     */
    public DuplicateItemException( )
    {
        super( );

    }
    /**
     * Construct this exception object.
     * @param message the error message.
     */
    public DuplicateItemException( String message )
    {
        super( message );
    }
}




声明: 除非注明,本文属( 阳光倾城 )原创,转载请保留链接: http://www.tomrrow.com/archives-7813.html