Raw Binary Tree Deletewithcopying Issue (Improved Explaination) - c++

Question

I've created Raw BinaryTree. In this tree, insertion is not like BST, its like this::
If tree is empty then add value & make it root. (suppose 30)
If tree is not empty then input father value (30) & add new value (20) to its left subtree.
If left subtree is not empty then, insert value (20) to right subtree.
For next insertion, again take father value to determine where value is to be added.
& so on..
Its working fine except when I try to delete a node with two children. Method Im using to delete is deleteWithCopy.
As my instructor has told, deletewithcopy is:
1. Find father of node (temp) which is to be deleted.
2. If temp (node to be deleted) is the right child of 'father' then find temp's immediate Successor
3. If temp (node to be deleted) is the left child of 'father' then find temp's immediate Predecessor
4. Swap value of temp with its predecessor/succesor
5. Delete temp (which is now leaf of tree).
NOW How to find Successor & Predecessor.
Successor = logical successor of a node is its right-most child in left subtree
Predecessor = logical predecessor of a node is its left-most child in right subtree
According to algorithm I have created the function, but after deleting, when I traverse (or print) the tree, it shows run time error,
Unhandled exception at 0x008B5853 in binarytree.exe: 0xC0000005: Access violation reading location 0xFEEEFEEE.
which is error for "0xFEEEFEEE is used to mark freed memory in Visual C++."
I have dry run-ed this thing again & again, there is nothing out of bounds in memory that Im trying to acces, I have fixed every loose end, but still :(
Here is the function:
void BinaryTree<mytype>::deletewithTwoChild(BTNode<mytype> *temp)
{
BTNode<mytype> *father = findfather(temp, root); //found address of father of temp node & stored it in pointer
BTNode<mytype> *leaf = temp; //created a copy of temp node
/////CASE 1 (for predecessor)
if(temp==root || father->left==temp) //if temp is left child of its father then
{
leaf = leaf->left; //move leaf 1 time left
while(leaf->right!=0 ) //until leaf reaches the right most node of left subtree
{
leaf = leaf->right; //move leaf 1 time to right
}
//swapping values
mytype var = leaf->key_value; //created a template variable to store leaf's key
leaf->key_value = temp->key_value; //assigning temp's key to leaf
temp->key_value = var; //assigning leaf's key to temp
if(leaf->right!=0) //if leaf has right child then call deletewithOneChild function
{
deletewithOneChild(leaf); //call to respective function
}
else if(leaf->left==0 && leaf->right==0) //if leaf has no children then
{
deleteWithNoChild(leaf); //call to respective function
}
}
/////CASE 2 (for successor)
else if(father->right==temp) //if temp is right child of its father, then
{
leaf = leaf->right; //move leaf 1 time right
while(leaf->left!=0) //until leaf reaches the last node of tree which has no child
{
leaf = leaf->left; //move leaf 1 time to left
}
//swapping values
mytype var = leaf->key_value; //created a template variable to store leaf's key
leaf->key_value = temp->key_value; //assigning temp's key to leaf
temp->key_value = var; //assigning leaf's key to temp
if(leaf->right!=0) //if leaf has right child then call deletewithOneChild function
{
deletewithOneChild(leaf); //call to respective function
}
else if(leaf->left==0 && leaf->right==0) //if leaf has no children then
{
deleteWithNoChild(leaf); //call to respective function
}
}
}
Data Set I m using:
30
/ \
20 80
/ / \
10 40 120
\ / \
60 100 140
/ \ / \
50 70 130 150
Im trying to delete node 80, 60, 120, 140 when the run time error pops up. Plz help :(( Also I need guidence how to handle tree iff 30 is deleted.

Answer 1

As I know, the definition of successor and predecessor are different.
Successor : the minimum node of right subtree, that is, the left-most node of right subtree.
Predecessor : the maximum node of left subtree, that is, the right-most node of left subtree.
Back to Issue 1. I have noticed the if-else condition after swapping values in case 1. Since, in case 1, you are finding the right most node of the subtree, leaf->right always be null and leaf->left may not be null. As a result, none of the delete function be called in case after swapping values. This will cause the issue of wrong BST or even worse, the crash of the program. Therefore, the if-else condition in case would be:
// leaf->right always be null, only need to verify leaf->left.
if (leaf->left != 0)
{
deleteWithOneNode(leaf);
}
else
{
deleteWithNoChild(leaf);
}
Issue 2. As I know, the remove of one node in BST has no rule to choose predecessor or successor and the parent(father) node of the removed node is used only when swapping the whole node rather then swapping the value of the node only. Therefore, my delete function would be:
void BinaryTree<myType>::delete(BTNode<myType>* node, BTNode<myType>* parent)
{
if (node->right) // find successor first
{
BTNode* ptrParent = node;
BTNode* ptr = node->right;
while (ptr->left)
{
ptrParnet = ptr;
ptr = ptr->left;
}
// Since the ptr will be delete, we only assign the value of ptr to the value node
node->key_value = ptr->key_value;
if (node == ptrParent)
{
ptrParnet->right = ptr->right;
}
else
{
ptrParent->left = ptr->right;
}
delete ptr;
}
else if (node->left) // find predecessor
{
BTNode* ptrParent = node;
BTNode* ptr = node->left;
while (ptr->right)
{
ptrParent = ptr;
ptr = ptr->right;
}
// Since the ptr will be delete, we only assign the value of ptr to the value node
node->key_value = ptr->key_value;
if (node == ptrParent)
{
ptrParent->left = ptr->left;
}
else
{
ptrParent->right = ptr->left;
}
delete ptr;
}
else
{
if (node->key_value > parent->key_value)
{
parent->right = NULL;
}
else
{
parent->left = NULL;
}
delete node;
}
}
By using the function, the tree after removing 30 would be
40
/ \
20 80
/ / \
10 60 120
/ \ / \
50 70 100 140
/ \
130 150