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#include "avl_tree.h"
#include <stdio.h>
#include <stdlib.h>
int max(int a, int b) {
return (a > b) ? a : b;
}
int height_of(AVLTree *tree) {
return tree == NULL ? 0 : tree->height;
}
AVLTree *smallest(AVLTree *tree) {
AVLTree *current = tree;
while (current->left != NULL)
current = current->left;
return current;
}
AVLTree *rotate_right(AVLTree *y) {
AVLTree *x = y->left;
AVLTree *t = x->right;
x->right = y;
y->left = t;
y->height = max(height_of(y->left), height_of(y->right)) + 1;
x->height = max(height_of(x->left), height_of(x->right)) + 1;
return x;
}
AVLTree *rotate_left(AVLTree *x) {
AVLTree *y = x->right;
AVLTree *t = y->left;
y->left = x;
x->right = t;
x->height = max(height_of(x->left), height_of(x->right)) + 1;
y->height = max(height_of(y->left), height_of(y->right)) + 1;
return y;
}
int balance_of(AVLTree *tree) {
return (tree == NULL) ? 0 : height_of(tree->left) - height_of(tree->right);
}
AVLTree *avl_tree_initialize(int value) {
AVLTree *tree = malloc(sizeof(AVLTree));
tree->value = value;
tree->left = NULL;
tree->right = NULL;
tree->height = 1;
return tree;
}
int avl_tree_size(AVLTree *tree) {
int total = 0;
if (tree == NULL)
return total;
if (tree->left)
total += avl_tree_size(tree->left);
if (tree->right)
total += avl_tree_size(tree->right);
return total + 1;
}
int compare(int a, int b)
{
return (a < b) ? -1 : ((a > b) ? 1 : 0);
}
AVLTree *avl_tree_insert(AVLTree *tree, int value) {
if (tree == NULL)
return avl_tree_initialize(value);
switch(compare(value, tree->value)) {
case -1:
tree->left = avl_tree_insert(tree->left, value);
break;
case 1:
tree->right = avl_tree_insert(tree->right, value);
break;
default:
return tree;
}
tree->height = 1 + max(height_of(tree->left), height_of(tree->right));
int balance = balance_of(tree);
if (balance > 1 && value < tree->left->value)
return rotate_right(tree);
if (balance < -1 && value > tree->right->value)
return rotate_left(tree);
if (balance > 1 && value > tree->left->value) {
tree->left = rotate_left(tree->left);
return rotate_right(tree);
}
if (balance < -1 && value < tree->right->value) {
tree->right = rotate_right(tree->right);
return rotate_left(tree);
}
return tree;
}
AVLTree *avl_tree_delete(AVLTree *tree, int value) {
if (tree == NULL)
return tree;
switch(compare(value, tree->value)) {
case -1:
tree->left = avl_tree_delete(tree->left, value);
break;
case 1:
tree->right = avl_tree_delete(tree->right, value);
break;
default:
if (tree->left && tree->right) {
AVLTree *min = smallest(tree->right);
tree->value = min->value;
tree->right = avl_tree_delete(tree->right, min->value);
} else {
AVLTree *tmp = tree->left ? tree->left : tree->right;
if (tmp) {
*tree = *tmp;
free(tmp);
} else {
free(tree);
return NULL;
}
}
break;
}
tree->height = 1 + max(height_of(tree->left), height_of(tree->right));
int balance = balance_of(tree);
if (balance > 1 && balance_of(tree->left) >= 0)
return rotate_right(tree);
if (balance > 1 && balance_of(tree->left) < 0) {
tree->left = rotate_left(tree->left);
return rotate_right(tree);
}
if (balance < -1 && balance_of(tree->right) <= 0)
return rotate_left(tree);
if (balance < -1 && balance_of(tree->right) > 0) {
tree->right = rotate_right(tree->right);
return rotate_left(tree);
}
return tree;
}
static void print_tree(AVLTree *tree, int level) {
for (int i = 0; i < level; i++)
printf(" ");
if (tree) {
printf("(%d:%d)\n", tree->value, tree->height);
if (!tree->left && !tree->right)
return;
print_tree(tree->left, level + 1);
print_tree(tree->right, level + 1);
}
else {
printf("( )\n");
}
}
static bool is_even(int value) {
return value % 2 == 0;
}
static bool is_odd(int value) {
return !is_even(value);
}
RBTree *_avl_tree_to_rb_tree(AVLTree *tree, AVLTree *parent) {
if (!tree)
return NULL;
enum Colour colour = (parent && is_even(parent->height) && is_odd(tree->height)) ? red : black;
RBTree *rb_tree = rb_tree_initialize_with(tree->value, colour);
rb_tree->left = _avl_tree_to_rb_tree(tree->left, tree);
rb_tree->right = _avl_tree_to_rb_tree(tree->right, tree);
return rb_tree;
}
RBTree *avl_tree_to_rb_tree(AVLTree *tree) {
if (!tree)
return NULL;
return _avl_tree_to_rb_tree(tree, NULL);
}
void avl_tree_inspect(AVLTree *tree) {
print_tree(tree, 0);
}
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