// Returns true if the value was found and removed, false if it was not found
bool HW4AVL::Remove(int dataValue)
{
if (!m_root)
{
return false;
}
// Implement (the rest of) this function
// Remember to balance before returning
Node* parent = NULL;
Node* deleteMe = m_root;
while (true)
{
if (deleteMe->Data == dataValue)
{
break;
}
else if (dataValue > deleteMe->Data)
{
if (deleteMe->Right)
{
parent = deleteMe;
deleteMe = deleteMe->Right;
}
else
{
return false;
}
}
else
{
if (deleteMe->Left)
{
parent = deleteMe;
deleteMe = deleteMe->Left;
}
else
{
return false;
}
}
}
// We have the node we want to delete and its parent
// Case 1: It's a leaf
if (NULL == deleteMe->Left && NULL == deleteMe->Right)
{
if (parent)
{
parent->DeleteChild(deleteMe);
}
else
{
delete m_root;
m_root = NULL;
}
}
// Case 2a: Null left child, non-null right
else if (NULL == deleteMe->Left)
{
if (parent)
{
parent->ReplaceAndDeleteChild(deleteMe, deleteMe->Right);
}
else
{
m_root = m_root->Right;
delete deleteMe;
}
}
// Case 2b: Null right child, non-null left
else if (NULL == deleteMe->Right)
{
if (parent)
{
parent->ReplaceAndDeleteChild(deleteMe, deleteMe->Left);
}
else
{
m_root = m_root->Left;
delete deleteMe;
}
}
// Case 3: Non-null left and right children
else
{
// (Arbitrary) Find the min in the right subtree
Node* min = deleteMe->Right;
while (min->Left)
{
min = min->Left;
}
int minValue = min->Data;
Remove(minValue);
deleteMe->Data = minValue;
return true;
}
// Check for balance & Balance if necessary
int lHeight = 0, rHeight = 0;
if(parent != NULL)
{
lHeight = Height(parent->Left);
rHeight = Height(parent->Right);
}
while(parent != NULL && (lHeight-rHeight) != 2 && (rHeight-lHeight) != 2)
{
parent = parent->Parent;
if(parent != NULL)
{
lHeight = Height(parent->Left);
rHeight = Height(parent->Right);
}
}
if(parent != NULL) //Need to balance
{
Node* child = NULL;
if(Height(parent->Left) > Height(parent->Right))
{
child = parent->Left;
}
else
{
child = parent->Right;
}
Node* grandChild = NULL;
if(Height(child->Left) > Height(child->Right))
{
grandChild = child->Left;
}
else
{
grandChild = child->Right;
}
if(child->Data < parent->Data)
{
if(grandChild->Data < child->Data)
{
rotateLeft(&parent);
}
else
{
rotateLeftTwice(&parent);
}
}
else
{
if(grandChild->Data > child->Data)
{
rotateRight(&parent);
}
else
{
rotateRightTwice(&parent);
}
}
}
return true;
}
