Thread: BST node deletion help!

this is my code snippet:

Code:

void deletenodebst(bst **rootptr,bst *node) {
bst *ptr, *ptr1;
	
	if(node->left==NULL || node->right==NULL){
	ptr = node;
	}else ptr = successorbst(node);
	
	if(ptr != NULL){
		if(ptr->left!=NULL){
		ptr1 = ptr->left;
		}
		else{
		ptr1 = ptr->right;
		}
	
		if(ptr->parent==NULL){
		*rootptr = ptr1;
		}
		else{
			if(ptr == ptr->parent->left){
			ptr->parent->left = ptr1;
			}
			else{
			ptr->parent->right = ptr1;
			}
		}
	}
	
	if(ptr!=node) node->value = ptr->value;
	free(ptr);
	
}

"bst *node" is the node to be deleted..

my problem is that when I try to perform this sequence:

Code:

insert 6
insert 20
insert 3
insert 2
insert 10
insert 100
insert 4
delete 20
delete 6
insert 16
insert 8
delete 8
delete 3
delete 16
delete 8
delete 4
delete 2
delete 10
delete 100

a "dumping stack trace" error occurs on the delete 2 part.. help please? thanks..

You set parent to point at ptr1, but you never set ptr1's parent back upwards (it will point at ptr, still, which is going to go away).

sorry for the late reply..

are you pertaining to this part?

Code:

else{
			if(ptr == ptr->parent->left){
			ptr->parent->left = ptr1;
                        //should I insert something here...
			}
			else{
			ptr->parent->right = ptr1;
                        //...or here?
			}
		}

can you explain it more? i'm sorry but i'm really having difficulty in getting this...

i get it. thanks.