private AVLNode SingleRotateWithRight(AVLNode k2) {
AVLNode k1;
k1 = k2.getRight();
k2.setRight(k1.getLeft());
k1.setLeft(k2);
k2.setHeight(Math.max(Height(k2.getLeft()), Height(k2.getRight())) + 1);
k1.setHeight(Math.max(Height(k1.getLeft()), k2.getHeight()) + 1);
return k1;
}
/**
* 1.如果是null节点，则直接返回null 2.如果删除的值<当前节点，则转入left节点进行递归删除 3.如果删除的值>当前节点，则转入right节点进行递归删除
* 4.如果删除的值为当前节点，如果当前节点只有一个子树，则直接返回该子树 5.如果删除的值为当前节点，且当前节点有两个子树，则将当前值更改为右子树中最小的节点值，并递归在右子树中删除该节点值
* 6.重新修正该处理节点的height值 7.对处理节点进行重新翻转处理，以修正在删除过程中可能出现的树不平衡情况
*
* @param x
* @param T
* @return
*/
private AVLNode remove(int x, AVLNode T) {
if (T == null) return null;
if (x < T.getValue()) {
T.setLeft(remove(x, T.getLeft()));
} else if (x > T.getValue()) {
T.setRight(remove(x, T.getRight()));
} else if (T.left != null && T.right != null) {
T.setValue(findMin(T.getRight()).getValue());
T.setRight(remove(T.getValue(), T.getRight()));
} else {
T = T.getLeft() == null ? T.getRight() : T.getLeft();
}
if (T != null) T.setHeight(Math.max(Height(T.getLeft()), Height(T.getRight())) + 1);
T = rotate(T);
return T;
}
/**
* @param element: The element to insert into the Tree
* @param temp: The AVLNode to evaluate for recursive insertion
* <p>This method recursively traverses the Tree, inserting the element at the appropriate
* spot and incrementing the balance factors for the subtrees as it evaluates. The Tree will
* then recursively rebalance as necessary.
*/
private void insert(E element, AVLNode<E> temp) {
if (this.rootAbove.getLeft() == null) {
this.rootAbove.setLeftNode(new AVLNode<E>(element));
return;
}
// travel left or right based on the
// comparison of element to temp.element
// remember that left means that element <= temp.element
// and right means element > temp.element
int compare = element.compareTo(temp.getElement());
// travel to the left of the Tree, inserting
// if the bottom has been reached
if (compare <= 0) {
// System.out.println(temp.getLeft());
if (temp.getLeft() == null) {
temp.setLeft(element);
return;
}
insert(element, temp.getLeft());
}
// otherwise, travelling to the right of the Tree,
// inserting if the bottom has been reached
else {
if (temp.getRight() == null) {
temp.setRight(element);
return;
}
insert(element, temp.getRight());
}
// if the root is being evaluated it, rotate if necessary
if (temp == rootAbove.getLeft()) {
rotate(rootAbove.getLeft(), rootAbove);
}
// otherwise, rotate the left and right subtrees
// as necessary
if (temp.getLeft() != null) {
rotate(temp.getLeft(), temp);
}
if (temp.getRight() != null) {
rotate(temp.getRight(), temp);
}
} // end insert
AVLNode insert(int x, AVLNode T) {
if (T == null) {
T = new AVLNode();
T.setValue(x);
T.setLeft(null);
T.setRight(null);
} else if (x < T.getValue()) {
T.setLeft(insert(x, T.getLeft()));
if (Height(T.getLeft()) - Height(T.getRight()) == 2) {
if (x < T.getLeft().getValue()) T = SingleRotateWithLeft(T);
else T = DoubleRotateWithLeft(T);
}
} else if (x > T.getValue()) {
T.setRight(insert(x, T.getRight()));
if (Height(T.getRight()) - Height(T.getLeft()) == 2)
if (x > T.getRight().getValue()) T = SingleRotateWithRight(T);
else T = DoubleRotateWithRight(T);
}
T.setHeight(Math.max(Height(T.getLeft()), Height(T.getRight())) + 1);
return T;
}
private AVLNode DoubleRotateWithRight(AVLNode k3) {
k3.setRight(SingleRotateWithLeft(k3.getRight()));
return SingleRotateWithRight(k3);
}