tree_t *rotateright(tree_t *p)
{
tree_t *q = p->left;
p->left = q->right;
q->right = p;
fixheight(p);
fixheight(q);
return q;
}
tree_t *rotateleft(tree_t *q)
{
tree_t *p = q->right;
q->right = p->left;
p->left = q;
fixheight(q);
fixheight(p);
return p;
}
void
deletemin (avltree ** n, void **dataptr)
{
avltree *temp;
short dif;
if ((*n)->left != NULL) /* keep going for leftmost node */
deletemin (&(*n)->left, dataptr);
else
{ /* leftmost node found */
*dataptr = (*n)->data; /* get pointer to data */
temp = *n;
*n = (*n)->right; /* return pointer to right subtree */
free (temp); /* of leftmost node */
}
if (*n != NULL)
{
fixheight (*n);
dif = difference (*n);
if (dif > 1) /* deletion caused left subtree to be too high */
balanceleft (n, -1);
else if (dif < -1) /* deletion caused right subtree to be too high */
balanceright (n, -1);
}
}
tree_t *balance(tree_t *p)
{
fixheight(p);
if (bfactor(p) == 2) {
if (bfactor(p->right) < 0)
p->right = rotateright(p->right);
return rotateleft(p);
}
if (bfactor(p) == -2) {
if (bfactor(p->left) > 0)
p->left = rotateleft(p->left);
return rotateright(p);
}
return p;
}
