• 周一. 8月 15th, 2022

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数据结构 二叉平衡树 avl双旋转

admin

11月 28, 2021

10,11,7,6,8,9

package tree.bst.avl;

public class AVLTreeDemo {
    public static void main(String[] args) {
        //int[] arr = {4,3,6,5,7,8};
        //int[] arr = {10,12,8,9,7,6};
        int[] arr = {10,11,7,6,8,9};
        AvlTree avlTree = new AvlTree();

        for (int i = 0; i < arr.length; i++) {
            avlTree.addNode(new Node(arr[i]));
        }

        // 中序遍历显示
        avlTree.infixOrder();

        // 求高度
        System.out.println(avlTree.getRoot().height());
        System.out.println(avlTree.getRoot().leftHeight());
        System.out.println(avlTree.getRoot().rightHeight());

        avlTree.infixOrder();

    }
}

class AvlTree {
    public Node getRoot() {
        return root;
    }

    public void setRoot(Node root) {
        this.root = root;
    }

    private Node root;

    public int height()
    {
        if (root == null){
            return 0;
        } else {
            return root.height();
        }
    }

    public void addNode(Node node) {
        if (root == null) {
            root = node;
        } else {
            root.add(node);
        }
    }

    public void infixOrder() {
        if (root == null) {
            return;
        }

        root.infixOrder();
    }

    public Node search(int value) {
        if (root == null) {
            return null;
        } else {
            return root.search(value);
        }
    }

    public Node searchParent(int value) {
        if (root == null) {
            return null;
        } else {
            return root.searchParent(value);
        }
    }

    /**
     * 删除最小节点
     *
     * @param node 传入的节点 当做一颗二叉排序书的根节点
     * @return 以node为根节点的的最小节点的值
     */
    public int delRightTreeMin(Node node) {
        Node temp = node;

        // 循环查找左子节点找到最小值
        while (temp.left != null) {
            temp = temp.left;
        }

        // delete the mini node
        deleteNode(temp.value);

        return temp.value;
    }

    public void deleteNode(int value) {
        if (root == null) {
            return;
        }

        // find thi node
        Node targetNode = this.search(value);
        // 如果没有找到要删除的节点
        if (targetNode == null) {
            return;
        }

        // 没有父节点
        if (root.left == null && root.right == null) {
            root = null;
            return;
        }

        Node parent = searchParent(value);

        //叶子节点
        if (targetNode.left == null && targetNode.right == null) {
            if (parent.left != null && parent.left.value == value) {
                parent.left = null;
            } else if (parent.right != null && parent.right.value == value) {
                parent.right = null;
            }
        } else if (targetNode.left != null && targetNode.right != null) { //两颗子树
            int min = this.delRightTreeMin(targetNode.right);
            targetNode.value = min;
        } else { // 一颗子树
            //  if has left node

            if (targetNode.left != null) {
                if (parent != null) {
                    // 如果targetNode是parent的左右
                    if (parent.left.value == value) {
                        parent.left = targetNode.left;
                    } else {
                        parent.right = targetNode.left;
                    }
                } else {
                    root = targetNode.left;
                }


            } else {
                if (parent != null) {
                    if (parent.right.value == value) {
                        parent.right = targetNode.right;
                    } else {
                        parent.left = targetNode.right;
                    }
                } else {
                    root = targetNode.right;
                }

            }
        }
    }

}


class Node {
    public int value;
    public Node left;
    public Node right;

    public Node(int value) {
        this.value = value;
    }

    public int leftHeight() {
        if (left == null) {
            return 0;
        } else {
            return left.height();
        }
    }
    // 左旋
    private void leftRotate()
    {
        //创建新的结点,以当前根结点的值
        Node newNode = new Node(value);
        //把新的结点的左子树设置成当前结点的左子树
        newNode.left = left;
        //把新的结点的右子树设置成带你过去结点的右子树的左子树
        newNode.right = right.left;
        //把当前结点的值替换成右子结点的值
        value = right.value;
        //把当前结点的右子树设置成当前结点右子树的右子树
        right = right.right;
        //把当前结点的左子树(左子结点)设置成新的结点
        left = newNode;
    }

    // 右旋
    private void rightRotate()
    {
        // 10  12 8 9 7 6 拿着转了玩
        Node newNode = new Node(value);
        newNode.right = right;
        newNode.left = left.right;
        value = left.value;
        left = left.left;
        right = newNode;
    }

    public int rightHeight() {
        if (right == null) {
            return 0;
        } else {
            return right.height();
        }
    }

    public int height() {
        return Math.max(this.left == null ? 0 : this.left.height(), this.right == null ? 0 : this.right.height()) + 1;
    }

    // find node
    public Node search(int value) {
        if (value == this.value) {
            return this;
        } else if (value < this.value) {
            // left tree find
            if (this.left == null) {
                return null;
            }
            return this.left.search(value);
        } else {
            if (this.right == null) {
                return null;
            }

            return this.right.search(value);
        }

    }

    // 查找要删除的节点的父节点
    public Node searchParent(int value) {
        if (this.left != null && this.left.value == value
                || (this.right != null && this.right.value == value)) {
            return this;
        } else {
            if (value < this.value && this.left != null) {
                return this.left.searchParent(value);
            } else if (value >= this.value && this.right != null) {
                return this.right.searchParent(value);
            } else {
                return null;
            }
        }
    }

    // 添加节点
    public void add(Node node) {
        if (node == null) {
            return;
        }

        // 添加 left
        if (node.value < this.value) {
            if (this.left == null) {
                this.left = node;
            } else {
                this.left.add(node);
            }
        }

        // 添加到right
        if (node.value > this.value) {
            if (this.right == null) {
                this.right = node;
            } else {
                this.right.add(node);
            }
        }

        // 添加完一个节点后 如果柚子树-左子树的高度>1 左旋转
        if(rightHeight() - leftHeight() > 1) {
            if(right!=null && right.leftHeight() > right.rightHeight()){
                right.left.rightRotate();
            }
            leftRotate();
        } else if(leftHeight() - rightHeight() > 1) {
           if(left !=null && left.rightHeight() > left.leftHeight()){
               left.leftRotate();
           }
           rightRotate();
        }

    }

    // 中序便利
    public void infixOrder() {
        if (this.left != null) {
            this.left.infixOrder();
        }

        System.out.println(this);

        if (this.right != null) {
            this.right.infixOrder();
        }
    }

    @Override
    public String toString() {
        return "Node{" +
                "value=" + value +
                '}';
    }
}

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