Binary search tree delete not working, why? - c

Question

I am trying to implement Binary search tree in C.
But I am stuck at the delete operation, when I run the code it doesn't delete the value specified.
Before calling delete:(calling inorder())
16 19 23
After calling delete:(calling inorder())
16 19 23
code:
void deleteNode(struct node *n, int data)
{
struct node *temp;
if(n->data==data)
{
if(n->left == NULL && n->right == NULL)
{
n=NULL;
}
else if(n->left == NULL && n->right!=NULL)
{
n->data = (n->right)->data;
n->right = NULL;
}
else if(n->left!=NULL && n->right == NULL)
{
n->data = (n->left)->data;
n->left=NULL;
}
else if(n->left != NULL && n->right != NULL)
{
temp = findMax(root);
n->data = temp->data;
temp = NULL;
}
}
else if(n->data > data)
{
deleteNode(n->left, data);
}
else if(n->data < data)
{
deleteNode(n->right, data);
}
}
I have other code which is working, but I want to know what is wrong with this code?
Edit:
I have edited the code with a few changes in it.
Now, When I try to delete the ROOT node.
I end up with this:
(inorder traversal)-> 16 23 23
Now,
Why is this happening when temp = NULL is making the maximum node NULL.
Note: I am not initializing temp as the code has been changed and it is initialized just before its use (temp = findMax(root)).
code inorder():
void inorder(struct node *root)
{
if(root!=NULL)
{
inorder(root->left);
printf("%d\n", root->data);
inorder(root->right);
}
}

Answer 1

Use this alternative code or use your temp tree in your method
struct node *temp = n; //then use temp tree in code
Alternative method
struct node *delete(struct node *tree, int data)
{
if(find(tree,data)==-1 || tree == NULL)
return tree;
if(tree->data == data)
{
if(tree->left==NULL && tree->right==NULL)
return NULL;
if(tree->right != NULL){
tree->data = min(tree->right);
tree->right = delete(tree->right,min(tree->right));
return tree;
}
tree->data = madata(tree->left);
tree->left = delete(tree->left,madata(tree->left));
return tree;
}
if(tree->data < data)
{
tree->right= delete(tree->right,data);
return tree;
}
tree->left= delete(tree->left,data);
return tree;
}

Answer 2

This is what worked for me,
struct node* deleteNode(struct node *n, int data)
{
struct node *temp;
temp = n;
if(n->data==data)
{
if(n->left == NULL && n->right == NULL)
{
n=NULL;
return NULL;
}
else if(n->left == NULL && n->right!=NULL)
{
n = n->right;
temp = NULL;
}
else if(n->left!=NULL && n->right == NULL)
{
n = n->left;
temp = NULL;
}
else if(n->left != NULL && n->right != NULL)
{
temp = findMax(root);
n->data = temp->data;
temp = NULL;
}
}
else if(n->data > data)
{
n->left = deleteNode(n->left, data);
}
else if(n->data < data)
{
n->right = deleteNode(n->right, data);
}
return n;
}