bag_elem_t avl_remove_min(avl_node_t **root)
{
bag_elem_t min;
if ((*root)->left) {
/* *root is not the minimum, keep going and rebalance if necessary. */
min = avl_remove_min(&(*root)->left);
if (HEIGHT((*root)->left) + 1 < HEIGHT((*root)->right))
avl_rebalance_to_the_left(root);
else
avl_update_height(*root);
} else {
/* Remove *root. */
avl_node_t *old = *root;
min = (*root)->elem;
*root = (*root)->right;
free(old);
}
return min;
}
static void do_rotation(struct avltree *tree, struct avlnode *parent)
{
struct avlnode *node;
/* do rotation */
while (parent) {
int balance;
struct avlnode *left, *right;
node = parent;
parent = node->parent;
left = node->left;
right = node->right;
balance = avl_balance(node);
if (balance < -1) {
int son_balance = avl_balance(right);
/* RR */
if (son_balance <= 0) {
if (!parent) {
lrotate(&tree->root);
} else {
lrotate(node == parent->left ? &parent->left : &parent->right);
}
continue;
}
/* RL */
if (son_balance > 0) {
rrotate(&node->right);
if (!parent) {
lrotate(&tree->root);
} else {
lrotate(node == parent->left ? &parent->left : &parent->right);
}
continue;
}
assert(0);
} else if (balance > 1) {
int son_balance = avl_balance(left);
/* LL */
if (son_balance >= 0) {
if (!parent) {
rrotate(&tree->root);
} else {
rrotate(node == parent->left ? &parent->left : &parent->right);
}
continue;
}
/* LR */
if (son_balance < 0) {
lrotate(&node->left);
if (!parent) {
rrotate(&tree->root);
} else {
rrotate(node == parent->left ? &parent->left : &parent->right);
}
continue;
}
assert(0);
} else {
avl_update_height(node);
}
}
}
