programming-examples/c++/Others/BinarySearchTree.cpp - Implementation for binary search tree.cpp

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2019-11-15 12:59:38 +01:00
BinarySearchTree.cpp - Implementation for binary search tree
#include "BinarySearchTree.h"
#include <iostream.h>
/**
* Implements an unbalanced binary search tree.
* Note that all "matching" is based on the < method.
*/
/**
* Construct the tree.
*/
template <class Comparable>
BinarySearchTree<Comparable>::BinarySearchTree( const Comparable & notFound ) :
root( NULL ), ITEM_NOT_FOUND( notFound )
{
}
/**
* Copy constructor.
*/
template <class Comparable>
BinarySearchTree<Comparable>::
BinarySearchTree( const BinarySearchTree<Comparable> & rhs ) :
root( NULL ), ITEM_NOT_FOUND( rhs.ITEM_NOT_FOUND )
{
*this = rhs;
}
/**
* Destructor for the tree.
*/
template <class Comparable>
BinarySearchTree<Comparable>::~BinarySearchTree( )
{
makeEmpty( );
}
/**
* Insert x into the tree; duplicates are ignored.
*/
template <class Comparable>
void BinarySearchTree<Comparable>::insert( const Comparable & x )
{
insert( x, root );
}
/**
* Remove x from the tree. Nothing is done if x is not found.
*/
template <class Comparable>
void BinarySearchTree<Comparable>::remove( const Comparable & x )
{
remove( x, root );
}
/**
* Find the smallest item in the tree.
* Return smallest item or ITEM_NOT_FOUND if empty.
*/
template <class Comparable>
const Comparable & BinarySearchTree<Comparable>::findMin( ) const
{
return elementAt( findMin( root ) );
}
/**
* Find the largest item in the tree.
* Return the largest item of ITEM_NOT_FOUND if empty.
*/
template <class Comparable>
const Comparable & BinarySearchTree<Comparable>::findMax( ) const
{
return elementAt( findMax( root ) );
}
/**
* Find item x in the tree.
* Return the matching item or ITEM_NOT_FOUND if not found.
*/
template <class Comparable>
const Comparable & BinarySearchTree<Comparable>::
find( const Comparable & x ) const
{
return elementAt( find( x, root ) );
}
/**
* Make the tree logically empty.
*/
template <class Comparable>
void BinarySearchTree<Comparable>::makeEmpty( )
{
makeEmpty( root );
}
/**
* Test if the tree is logically empty.
* Return true if empty, false otherwise.
*/
template <class Comparable>
bool BinarySearchTree<Comparable>::isEmpty( ) const
{
return root == NULL;
}
/**
* Print the tree contents in sorted order.
*/
template <class Comparable>
void BinarySearchTree<Comparable>::printTree( ) const
{
if( isEmpty( ) )
cout << "Empty tree" << endl;
else
printTree( root );
}
/**
* Deep copy.
*/
template <class Comparable>
const BinarySearchTree<Comparable> &
BinarySearchTree<Comparable>::
operator=( const BinarySearchTree<Comparable> & rhs )
{
if( this != &rhs )
{
makeEmpty( );
root = clone( rhs.root );
}
return *this;
}
/**
* Internal method to get element field in node t.
* Return the element field or ITEM_NOT_FOUND if t is NULL.
*/
template <class Comparable>
const Comparable & BinarySearchTree<Comparable>::
elementAt( BinaryNode<Comparable> *t ) const
{
if( t == NULL )
return ITEM_NOT_FOUND;
else
return t->element;
}
/**
* Internal method to insert into a subtree.
* x is the item to insert.
* t is the node that roots the tree.
* Set the new root.
*/
template <class Comparable>
void BinarySearchTree<Comparable>::
insert( const Comparable & x, BinaryNode<Comparable> * & t ) const
{
if( t == NULL )
t = new BinaryNode<Comparable>( x, NULL, NULL );
else if( x < t->element )
insert( x, t->left );
else if( t->element < x )
insert( x, t->right );
else
; // Duplicate; do nothing
}
/**
* Internal method to remove from a subtree.
* x is the item to remove.
* t is the node that roots the tree.
* Set the new root.
*/
template <class Comparable>
void BinarySearchTree<Comparable>::
remove( const Comparable & x, BinaryNode<Comparable> * & t ) const
{
if( t == NULL )
return; // Item not found; do nothing
if( x < t->element )
remove( x, t->left );
else if( t->element < x )
remove( x, t->right );
else if( t->left != NULL && t->right != NULL ) // Two children
{
t->element = findMin( t->right )->element;
remove( t->element, t->right );
}
else
{
BinaryNode<Comparable> *oldNode = t;
t = ( t->left != NULL ) ? t->left : t->right;
delete oldNode;
}
}
/**
* Internal method to find the smallest item in a subtree t.
* Return node containing the smallest item.
*/
template <class Comparable>
BinaryNode<Comparable> *
BinarySearchTree<Comparable>::findMin( BinaryNode<Comparable> *t ) const
{
if( t == NULL )
return NULL;
if( t->left == NULL )
return t;
return findMin( t->left );
}
/**
* Internal method to find the largest item in a subtree t.
* Return node containing the largest item.
*/
template <class Comparable>
BinaryNode<Comparable> *
BinarySearchTree<Comparable>::findMax( BinaryNode<Comparable> *t ) const
{
if( t != NULL )
while( t->right != NULL )
t = t->right;
return t;
}
/**
* Internal method to find an item in a subtree.
* x is item to search for.
* t is the node that roots the tree.
* Return node containing the matched item.
*/
template <class Comparable>
BinaryNode<Comparable> *
BinarySearchTree<Comparable>::
find( const Comparable & x, BinaryNode<Comparable> *t ) const
{
if( t == NULL )
return NULL;
else if( x < t->element )
return find( x, t->left );
else if( t->element < x )
return find( x, t->right );
else
return t; // Match
}
/****** NONRECURSIVE VERSION*************************
template <class Comparable>
BinaryNode<Comparable> *
BinarySearchTree<Comparable>::
find( const Comparable & x, BinaryNode<Comparable> *t ) const
{
while( t != NULL )
if( x < t->element )
t = t->left;
else if( t->element < x )
t = t->right;
else
return t; // Match
return NULL; // No match
}
*****************************************************/
/**
* Internal method to make subtree empty.
*/
template <class Comparable>
void BinarySearchTree<Comparable>::
makeEmpty( BinaryNode<Comparable> * & t ) const
{
if( t != NULL )
{
makeEmpty( t->left );
makeEmpty( t->right );
delete t;
}
t = NULL;
}
/**
* Internal method to print a subtree rooted at t in sorted order.
*/
template <class Comparable>
void BinarySearchTree<Comparable>::printTree( BinaryNode<Comparable> *t ) const
{
if( t != NULL )
{
printTree( t->left );
cout << t->element << endl;
printTree( t->right );
}
}
/**
* Internal method to clone subtree.
*/
template <class Comparable>
BinaryNode<Comparable> *
BinarySearchTree<Comparable>::clone( BinaryNode<Comparable> * t ) const
{
if( t == NULL )
return NULL;
else
return new BinaryNode<Comparable>( t->element, clone( t->left ), clone( t->right ) );
}