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package datastructures.binarytree;/** * 演示二叉树的操作 */public class BinaryTree {    /**     * 根节点     */    private Node root;    /**     * 查找一个节点     * @param key 要查找的id值     * @return     */    public Node find(int key){        //当前节点        Node current = root;        while(current.getId()!=key){            if(current.getId() > key){                current = current.getLeftChild();            }else if(current.getId() < key){                current = current.getRightChild();            }            if(current == null){                return null;            }        }               return current;    }    /**     * 插入一个节点     * @param id     * @param data     */    public void insert(int id,int data){        //1：先创建一个新节点        Node newNode = new Node(id,data);        if(root == null){            root = newNode;        }else{            //2：查找要插入的位置                    Node current = root;            Node parent = null;            while(true){                parent = current;                if(id < current.getId()){                    current = current.getLeftChild();                    //如果没有左子节点                    if(current == null){                        //3：修改相应的节点的属性                        parent.setLeftChild(newNode);                        return;                    }                }else{                    current = current.getRightChild();                    if(current==null){                        //3：修改相应的节点的属性                        parent.setRightChild(newNode);                        return;                    }                }            }        }    }    /**     * 前序获取节点数据     * @param node     */    public void preOrder(Node node){        if(node != null){            System.out.println(node.getId()+" - ");            preOrder(node.getLeftChild());            preOrder(node.getRightChild());        }    }    /**     * 中序获取节点数据     * @param node     */    public void inOrder(Node node){        if(node != null){            inOrder(node.getLeftChild());            System.out.println(node.getId()+" - ");            inOrder(node.getRightChild());        }    }    /**     * 后序获取节点数据     * @param node     */    public void postOrder(Node node){        if(node != null){            postOrder(node.getLeftChild());            postOrder(node.getRightChild());            System.out.println(node.getId()+" - ");        }    }    /**     * 获取最小节点     * @return     */    public Node getMinNode(){        Node current = root;        Node lastNode = null;        while(current!=null){            lastNode = current;            current = current.getLeftChild();        }        return lastNode;    }    /**     * 获取最大节点     * @return     */    public Node getMaxNode(){        Node current = root;        Node lastNode = null;        while(current!=null){            lastNode = current;            current = current.getRightChild();        }        return lastNode;    }    /**     * 删除一个节点     * @param key     * @return     */    public boolean delete(int key){        //1：找到要删除的节点        Node current = root;        Node parent = root;        boolean isLeftChild = true;        while(current.getId()!=key){            parent = current;            if(current.getId() > key){                isLeftChild = true;                current = current.getLeftChild();            }else if(current.getId() < key){                isLeftChild = false;                current = current.getRightChild();            }            if(current == null){                return false;            }        }        //2：没有子节点        if(current.getLeftChild()==null && current.getRightChild()==null){            this.noChildren(parent, current, isLeftChild);        }               //3：只有一个子节点        //只有左节点        else if(current.getRightChild()== null){            this.oneLeftChild(parent, current, isLeftChild);        }        //只有右节点        else if(current.getLeftChild() == null){            this.oneRightChild(parent, current, isLeftChild);        }        //4：有两个子节点        else{            //4.1：找到中序后继节点            Node successor = this.getSuccessor(current);            if(current == root){                root = successor;            }else{                if(isLeftChild){                    parent.setLeftChild(successor);                }else{                    parent.setRightChild(successor);                }            }            //重新设置successor的leftChild            successor.setLeftChild(current.getLeftChild());        }        return true;    }    /**     * 找到要删除节点的中序后继节点     * @param delNode     * @return     */    private Node getSuccessor(Node delNode){        Node successor = delNode;        Node successorParent = delNode;        Node current = delNode.getRightChild();        //查找节点        while(current!=null){            successorParent = successor;            successor = current;            current = current.getLeftChild();        }        //设置相应的值        if(successor!=delNode.getRightChild()){            successorParent.setLeftChild(successor.getRightChild());            successor.setRightChild(delNode.getRightChild());        }        return successor;    }    private void oneRightChild(Node parent,Node current,boolean isLeftChild){        if(current == root){            root = current.getRightChild();        }else{            if(isLeftChild){                parent.setLeftChild(current.getRightChild());            }else{                parent.setRightChild(current.getRightChild());            }        }    }    private void oneLeftChild(Node parent,Node current,boolean isLeftChild){        if(current == root){            root = current.getLeftChild();        }else{            if(isLeftChild){                parent.setLeftChild(current.getLeftChild());            }else{                parent.setRightChild(current.getLeftChild());            }        }    }    private void noChildren(Node parent,Node current,boolean isLeftChild){        if(current == root){            root = null;        }else{            if(isLeftChild){                parent.setLeftChild(null);            }else{                parent.setRightChild(null);            }        }    }    public static void main(String[] args) {        BinaryTree t = new BinaryTree();        t.insert(6,6);        t.insert(5,2);        t.insert(8,2433);        t.insert(3, 5);        t.insert(7,77);        t.insert(9,233);//      System.out.println(t.root.toString());//      //      t.inOrder(t.find(6));//      //      Node min = t.getMinNode();//      Node max = t.getMaxNode();//      System.out.println("min=="+min);//      System.out.println("max=="+max);        t.delete(8);        System.out.println(t.root.toString());    }}