平衡二叉树 JAVA实现 亲测可用

平衡二叉树的JAVA实现 亲测可用 包括LL LR RL RR四种情况的旋转算法 以及添加删除树结点之后对平衡二叉树的维护算法

都已经实现并测试过 没有问题。

代码地址可以直接上我的GIT clone:

https://github.com/bolddream/algorithm/tree/master/TreeHandler

以下附上class AVLTree 的实现代码：

public class AVLTree<T extends Comparable<T>>
{

    public TreeNode<T> rootNode;

    public int getMaxHeight(TreeNode<T> root)
    {
        if(root == null)
        {
            return 0;
        }

        int height = 1;
        int leftSonHeight = getMaxHeight(root.lson);
        int rightSonHeight = getMaxHeight(root.rson);
        if(leftSonHeight > rightSonHeight)
        {
            height += leftSonHeight;
        }
        else
        {
            height += rightSonHeight;
        }

        return height;
    }

    public TreeNode<T> singleRotateLeft(TreeNode<T> k2)
    {
        TreeNode<T> k1 = k2.lson;
        if(k1 == null)
        {
            return null;
        }

        TreeNode<T> temp = k1.rson;
        k1.rson = k2;
        k2.lson = temp;

        k2.height = getMaxHeight(k2);
        k1.height = getMaxHeight(k1);
        return k1;
    }

    public TreeNode<T> singleRotateRight(TreeNode<T> k2)
    {
        TreeNode<T> k1 = k2.rson;
        if(k1 == null)
        {
            return null;
        }

        TreeNode<T> temp = k1.lson;
        k1.lson = k2;
        k2.rson = temp;

        k2.height = getMaxHeight(k2);
        k1.height = getMaxHeight(k1);
        return k1;
    }

    public TreeNode<T> doubleRotateLeftRight(TreeNode<T> k3)
    {
        k3.lson = singleRotateRight(k3.lson);
        return singleRotateLeft(k3);
    }

    public TreeNode<T> doubleRotateRightLeft(TreeNode<T> k3)
    {
        k3.rson = singleRotateLeft(k3.rson);
        return singleRotateRight(k3);
    }

    public TreeNode<T> insertTreeNode(TreeNode<T> insertNode)
    {
        return insertTreeNode(insertNode, this.rootNode);
    }

    public TreeNode<T> insertTreeNode(TreeNode<T> insertNode, TreeNode<T> currentNode)
    {
        if(insertNode == null)
        {
            return currentNode;
        }

        TreeNode<T> rootNode = currentNode;
        if(currentNode == null)
        {
            currentNode = insertNode;
            currentNode.height = 1;
            currentNode.freq = 1;
            rootNode = currentNode;
            return rootNode;
        }

        if(insertNode.data.compareTo(currentNode.data) > 0)
        {
            currentNode.rson = insertTreeNode(insertNode, currentNode.rson);
            currentNode.height = getMaxHeight(currentNode);
            rootNode = ajustAVLTree(currentNode);
        }
        else if(insertNode.data.compareTo(currentNode.data) < 0)
        {
            currentNode.lson = insertTreeNode(insertNode, currentNode.lson);
            currentNode.height = getMaxHeight(currentNode);
            rootNode = ajustAVLTree(currentNode);
        }
        else
        {
            currentNode.freq ++;
            rootNode = currentNode;
        }

        return rootNode;

    }

    public TreeNode<T> ajustAVLTree(TreeNode<T> currentNode)
    {
        TreeNode<T> rootNode = currentNode;

        int leftSonHeight = (currentNode.lson != null) ? currentNode.lson.height : 0;
        int rightSonHeight = (currentNode.rson != null) ? currentNode.rson.height : 0;
        if(2 == rightSonHeight - leftSonHeight)
        {
            int rightLeftSonHeight = (currentNode.rson.lson != null) ? currentNode.rson.lson.height : 0;
            int rightRightSonHeight = (currentNode.rson.rson != null) ? currentNode.rson.rson.height : 0;

            if(rightLeftSonHeight > rightRightSonHeight)
            {
                //RL
                rootNode = doubleRotateRightLeft(currentNode);
            }
            else
            {
                //RR
                rootNode = singleRotateRight(currentNode);
            }
        }
        else if(2 == leftSonHeight - rightSonHeight)
        {
            int leftLeftSonHeight = (currentNode.lson.lson != null) ? currentNode.lson.lson.height : 0;
            int leftRightSonHeight = (currentNode.lson.rson != null) ? currentNode.lson.rson.height : 0;

            if(leftLeftSonHeight > leftRightSonHeight)
            {
                //LL
                rootNode = singleRotateLeft(currentNode);
            }
            else
            {
                //LR
                rootNode = doubleRotateLeftRight(currentNode);
            }
        }

        return rootNode;
    }

    public TreeNode<T> deleteTreeNode(TreeNode<T> deleteNode, TreeNode<T> currentNode)
    {
        if(deleteNode == null || currentNode == null)
        {
            return currentNode;
        }

        TreeNode<T> rootNode;

        if(deleteNode.data.compareTo(currentNode.data) > 0)
        {
            currentNode.rson = deleteTreeNode(deleteNode, currentNode.rson);
            currentNode.height = getMaxHeight(currentNode);

            rootNode = ajustAVLTree(currentNode);
        }
        else if(deleteNode.data.compareTo(currentNode.data) < 0)
        {
            currentNode.lson = deleteTreeNode(deleteNode, currentNode.lson);
            currentNode.height = getMaxHeight(currentNode);

            rootNode = ajustAVLTree(currentNode);
        }
        else
        {
            if(currentNode.freq >=2)
            {
                currentNode.freq--;
            }
            else
            {
                TreeNode<T> temp = currentNode;
                if(currentNode.lson != null && currentNode.rson != null)
                {
                    //get the min value node of right son tree, then replace the currentNode;
                    TreeNode<T> minValueRightSon;
                    temp = currentNode.rson;
                    while(temp.lson != null)
                    {
                        minValueRightSon = temp;
                        temp = temp.lson;
                    }

                    currentNode.data = temp.data;
                    currentNode.freq = temp.freq;
                    currentNode.rson = deleteTreeNode(temp, currentNode.rson);
                }
                else if(currentNode.lson == null)
                {
                    currentNode = currentNode.rson;
                }
                else
                {
                    currentNode = currentNode.lson;
                }

                if(currentNode != null)
                {
                    currentNode.height = getMaxHeight(currentNode);
                    currentNode = ajustAVLTree(currentNode);
                }

            }
            rootNode = currentNode;
        }

        return rootNode;
    }

    public TreeNode<T> middleSearchTreeNode(T searchData, TreeNode<T> currentNode)
    {
        if(currentNode == null)
        {
            return null;
        }

        TreeNode<T> result = null;
        if(searchData.equals(currentNode.data))
        {
            return currentNode;
        }
        else
        {
            result = middleSearchTreeNode(searchData, currentNode.lson);
            if(result == null)
            {
                result = middleSearchTreeNode(searchData, currentNode.rson);
            }
        }

        return result;
    }

    public void middleTraverseTree(TreeNode<T> rootNode)
    {
        if(rootNode == null)
        {
            return ;
        }

        if(rootNode.data != null)
        {
            System.out.print(rootNode.data.toString() + "  ");
        }

        middleTraverseTree(rootNode.lson);
        middleTraverseTree(rootNode.rson);
     }
}

树结点的class TreeNode 定义：

public class TreeNode<T> {
    public TreeNode(T data) {
        this.data = data;
    }
    public T data;
    public int freq;
    public int height;
    public TreeNode<T> lson;
    public TreeNode<T> rson;
}