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#include <lib/algo/avl_tree.h>
#include <lib/monad.h>
#include <stddef.h>
#include <stdio.h>
// Get the height of an AVL node
AvlHeight_t get_height(AVLNode *node) {
if (node == NULL) {
return 0;
}
return node->height;
}
// Get the Maximum Height between two
AvlHeight_t max_height(AvlHeight_t a, AvlHeight_t b) { return (a > b) ? a : b; }
// Get the balance factor of a node
ssize_t get_balance_factor(AVLNode *node) {
if (node == NULL) {
return 0;
}
return get_height(node->left) - get_height(node->right);
}
// Rotate an AVL node right
AVLNode *right_rotate(AVLNode *parent) {
AVLNode *child1 = parent->left;
AVLNode *child2 = child1->right;
child1->right = parent;
parent->left = child2;
parent->height =
max_height(get_height(parent->left), get_height(parent->right)) + 1;
child1->height =
max_height(get_height(child1->left), get_height(child1->right)) + 1;
return child1;
}
// Rotate an AVL node left
AVLNode *left_rotate(AVLNode *parent) {
AVLNode *child1 = parent->right;
AVLNode *child2 = child1->left;
child1->left = parent;
parent->right = child2;
parent->height =
max_height(get_height(parent->left), get_height(parent->right)) + 1;
child1->height =
max_height(get_height(child1->left), get_height(child1->right)) + 1;
return child1;
}
// Create AVL node
AVLNode *create_avl_node(void *data, AvlComparator compare) {
AVLNode *node = (AVLNode *)malloc(sizeof(AVLNode));
if (node == NULL) {
return NULL;
}
node->data = data;
node->compare = compare;
node->left = NULL;
node->right = NULL;
node->height = 1; // Leaf initially
return node;
}
// Insert data into AVL tree
Result avl_insert(AVLNode *node, void *data, AvlComparator compare) {
Result result;
// 1. Standard BST insertion
if (node == NULL) {
return (Result){create_avl_node(data, compare), TRUE};
}
if (node->compare(data, node->data)) {
result = avl_insert(node->left, data, compare);
if (!result.success) {
fprintf(stderr, "Failed to insert!");
return result;
}
node->left = (AVLNode *)result.data;
} else if (node->compare(node->data, data)) {
result = avl_insert(node->right, data, compare);
if (!result.success) {
fprintf(stderr, "Failed to insert!");
return result;
}
node->right = (AVLNode *)result.data;
} else {
return (Result){node, FALSE};
}
// 2. Update height of the ancestor node
node->height =
1 + max_height(get_height(node->left), get_height(node->right));
ssize_t balance = get_balance_factor(node);
// 4. If the node becomes unbalanced
// LeftLeft
if ((balance > 1) && node->compare(data, node->left->data)) {
return (Result){right_rotate(node), TRUE};
}
// RightRight
if ((balance < -1) && node->compare(node->right->data, data)) {
return (Result){left_rotate(node), TRUE};
}
// LeftRight
if ((balance > 1) && node->compare(node->left->data, data)) {
return (Result){right_rotate(node), TRUE};
}
// RightLeft
if ((balance < -1) && node->compare(data, node->right->data)) {
return (Result){left_rotate(node), TRUE};
}
return (Result){node, TRUE};
}
// In-order traversal print pointer
void print_in_order(AVLNode *root) {
if (root != NULL) {
print_in_order(root->left);
printf("%p ", root->data);
print_in_order(root->right);
}
}
// Free avl tree nodes starting at root
void free_avl_tree(AVLNode *root) {
if (root != NULL) {
free_avl_tree(root->left);
free_avl_tree(root->right);
free(root);
}
}
// Free avl tree and their data starting at root
void free_avl_tree_nodes(AVLNode *root) {
if (root != NULL) {
free_avl_tree_nodes(root->left);
free_avl_tree_nodes(root->right);
if (root->data != NULL) {
free(root->data);
}
free(root);
}
}
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