AVL平衡树的插入例程

/*
**AVL平衡树插入例程
**2014-5-30 11:44:50
*/

avlTree insert(elementType X, avlTree T){
	if(T == NULL){
		T = malloc(sizeof(struct avlTree));
		if(T == NULL) fatalError("Out of space!!!");
		T->element = X; T->height = 0;
		T->left = T->right = NULL;
	}else if(X < T->element){
		T->left = insert(X, T->left);
		if(height(T->left) - height(T->right) == 2){
			if(X < T->left->element)
				T = singleRotateWithLeft(T);
			else T = doubleRotateWithLeft(T);
		}
	}else if(X > T->element){
		T->right = insert(X, T->right);
		if(height(T->right) - height(T->left) == 2){
			if(X > T->right->element)
				T = singleRotateWithRight(T);
			else T = doubleRotateWithRight(T);
		}
	}
	/*--假设X已经存在，那么啥都不用做--*/

	T->height = max(height(T->left), height(T->right)) + 1;
	return T;
}

static position singleRotateWithLeft(position k2){
	position k1 = k2-> left;
	k2->left = k1->right;
	k1->right = k2;

	k2->height = max(height(k2->left), height(k2->right)) + 1;
	k1->height = max(height(k1->left), k2->height) + 1;
	return k1;
}

/*双右左旋就是先对T的右子树左单旋再对T本身右单旋*/
static position