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#pragma once
#include "StdAfx.h"
struct TreeNode;
template <class ItemType>
class TreeType
{
public:
TreeType(void);
~TreeType(void);
void InsertItem(ItemType item);
void Insert (TreeNode<ItemType>*& tree, ItemType item, bool & taller);
void RightBalance (TreeNode<ItemType> *& tree, bool & taller);
void LeftBalance (TreeNode<ItemType> *& tree, bool & taller);
void RotateLeft (TreeNode<ItemType> * & tree);
void RotateRight (TreeNode<ItemType> * & tree);
//private:
//TreeNode<ItemType>*& tree;
};
template <class ItemType>
void TreeType<ItemType>::InsertItem(ItemType item)
// Calls recursive function Insert to insert item into tree.
{
bool taller;
Insert (root, item, taller);
}
template <class ItemType>
void TreeType<ItemType>::Insert (TreeNode<ItemType>*& tree, ItemType item, bool & taller)
// Inserts item into tree.
// Post: item is in tree; search property is maintained.
{
if (tree == NULL)
{ // Insertion place found.
tree = new TreeNode<ItemType>;
tree->left = NULL;
tree->right = NULL;
tree->info = item;
tree->bf = EH;
taller = true;
}
else if ( item == tree->info)
{
cerr << "Duplicate key is not allowed in AVL tree." << endl;
}
else if (item < tree->info)
{
Insert (tree->left, item, taller);
if (taller)
switch (tree->bf)
{
case LH: LeftBalance (tree, taller);
break;
case EH:
tree->bf = LH;
break;
case RH:
tree->bf = EH;
taller = false;
break;
}
}
else if (item > tree->info)
{
Insert (tree->right, item, taller);
if (taller)
switch (tree->bf)
{
case RH:
RightBalance (tree, taller);
break;
case EH:
tree->bf = RH;
break;
case LH:
tree->bf = EH; taller = false;
break;
}
}
template <class ItemType>
void TreeType<ItemType>::RightBalance (TreeNode<ItemType> *& tree, bool & taller)
{
TreeNode<ItemType> * rs = tree->right;
TreeNode<ItemType> * ls;
switch (rs->bf)
{
case RH: tree->bf = rs->bf = EH;
RotateLeft(tree);
taller = false;
break;
case EH: cerr << "Tree already balanced " << endl;
break;
case LH: ls = rs->left;
switch (ls->bf)
{
case RH:
tree->bf = LH;
rs->bf = EH;
break;
case EH:
tree->bf = rs->bf = EH;
break;
case LH:
tree->bf = EH;
rs->bf = RH;
break;
}
ls->bf = EH;
RotateRight(tree->right);
RotateLeft(tree);
taller = false;
}
}
template <class ItemType>
void TreeType<ItemType>::LeftBalance (TreeNode<ItemType> *& tree, bool & taller)
{
TreeNode<ItemType> * ls = tree->left;
TreeNode<ItemType> * rs;
switch (ls->bf)
{
case LH:
tree->bf = ls->bf = EH;
RotateRight(tree);
taller = false;
break;
case EH:
cerr << "Tree already balanced " << endl;
break;
case RH:
rs = ls->left;
switch (rs->bf)
{
case LH:
tree->bf = RH;
ls->bf = EH;
break;
case EH:
tree->bf = ls->bf = EH;
break;
case RH:
tree->bf = EH;
ls->bf = LH;
break;
}
rs->bf = EH;
RotateLeft(tree->left);
RotateRight(tree);
taller = false;
}
}
template <class ItemType>
void TreeType<ItemType>::RotateLeft (TreeNode<ItemType> * & tree)
{
TreeNode<ItemType> * rs;
if (tree == NULL)
cerr << "Cannot rotate an empty tree in RotateLeft" << endl;
else if (tree->right == NULL)
cerr << "Cannot make an empty subtree the root in RotateLeft" << endl;
else
{
rs = tree->right;
tree->right = rs->left;
rs->left = tree;
tree = rs;
}
}
template <class ItemType>
void TreeType<ItemType> :: RotateRight (TreeNode<ItemType> * & tree)
{
TreeNode<ItemType> * ls;
if (tree == NULL)
cerr << "Cannot rotate an empty tree in RotateRight" << endl;
else if (tree->left == NULL)
cerr << "Cannot make an empty subtree the root in RotateRight" << endl;
else
{
ls = tree->left;
tree->left = ls->right;
ls->right = tree;
tree = ls;
}
}
}
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