View AVL tree not giving the correct output - c

Question

I am working on a school project that involves implementing an AVL Tree with the functions to insert delete and view. But my program didnt give the correct output when viewing the avl tree with preorder traversal.
The variable for avl tree:
typedef struct Node{
int data;
int height;
struct Node *right;
struct Node *left;
}Node;
Here is my insert function with newnode function call:
Node *newNode(int data){
Node *node = (Node*)malloc(sizeof(Node));
node->data = data;
node->left = NULL;
node->right = NULL;
node->height = 1;
return(node);
}
Node *insertNode(Node *node, int data){
if(node == NULL)
return(newNode(data));
if(data < node->data)
node->left = insertNode(node->left, data);
if(data > node->data)
node->right = insertNode(node->right, data);
if(data == node->data){
printf("No duplicate allowed.");
return node;
}
node->height = getHeight(node);
return(balancing(node, data));
}
Delete function with minvaluenode function call:
Node * minValueNode(Node* node){
Node* current = node;
while (current->left != NULL)
current = current->left;
return current;
}
Node *deleteNode(Node *root, int data){
if(root == NULL){
printf("Value not found.");
return root;
}
else if ( data < root->data )
root->left = deleteNode(root->left, data);
else if( data > root->data )
root->right = deleteNode(root->right, data);
else if(data == root->data){
if( (root->left == NULL) || (root->right == NULL) ){
Node *temp = root->left ? root->left : root->right;
if (temp == NULL){
temp = root;
root = NULL;
}
else
*root = *temp;
free(temp);
}
else{
Node* temp = minValueNode(root->right);
root->data = temp->data;
root->right = deleteNode(root->right,temp->data);
}
}
if(root == NULL)
return root;
root->height = getHeight(root);
return(balancing(root, data));
}
Balancing function with rotate,getbalancefactor, max, and getheight function calls:
int max(int number1, int number2){
return (number1 > number2) ? number1 : number2;
}
int getHeight(Node* n) {
return max(height(n->left), height(n->right)) + 1;
}
int getBalanceFactor(Node *currentNode){
if(currentNode == NULL)
return 0;
return height(currentNode->left) - height(currentNode->right);
}
Node *rightRotate(Node *currentNode){
Node *temp = currentNode->left;
currentNode->left = temp->right;
temp->right = currentNode;
temp->height = getHeight(temp);
currentNode->height = getHeight(currentNode);
return temp;
}
Node *leftRotate(Node *currentNode){
Node *temp = currentNode->right;
currentNode->right = temp->left;
temp->left = currentNode;
temp->height = getHeight(temp);
currentNode->height = getHeight(currentNode);
return temp;
}
Node *balancing(Node *node, int data){
if(getBalanceFactor(node) >= 2 && data < node->left->data)
return rightRotate(node);
if(getBalanceFactor(node) <= -2 && data > node->right->data)
return leftRotate(node);
if(getBalanceFactor(node) >= 2 && data > node->left->data){
node->left = leftRotate(node->left);
return(rightRotate(node));
}
if(getBalanceFactor(node) <= -2 && data < node->right->data){
node->right = rightRotate(node->right);
return(leftRotate(node));
}
return node;
}
My view function:
//print AVL Tree in preorder traversal
void printAVLTree(Node *root){
if(root != NULL)
{
printf("%d ", root->data);
printAVLTree(root->left);
printAVLTree(root->right);
}
}
I made a test with random insert input:
9 5 10 6 0 11 -1 1 2
The output when calling the view function is:
5 1 0 -1 2 9 6 10 11
The correct output should be:
9 1 0 -1 5 2 6 10 11

Answer 1

Your mistake is that you are updating the height values in the wrong order (top to bottom):
temp->height = getHeight(temp);
currentNode->height = getHeight(currentNode);
After rotation, the lower node is currentNode so you have to update it first.
Otherwise, if you update temp before updating currentNode, temp will use the previous value of currentNode height and will have a wrong height