二叉查找树（二叉排序树）Java实现

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package com.demo;/** * 二叉排序树（查找树） */public class BiTree {    private BiNode root;    public void insertNode(int data){        BiNode node = new BiNode(data, null, null);        if(root == null){            root = node;        }else{            BiNode currentNode = root;            BiNode parentNode;            while(true){                parentNode = currentNode;                if(data < currentNode.data){                    if((currentNode = currentNode.lchild) != null){                        continue;                    }else{                        parentNode.lchild = node;                        return;                    }                }else{                    if((currentNode = currentNode.rchild) != null){                        continue;                    }else{                        parentNode.rchild = node;                        return;                    }                }            }        }    }    //删除节点    public void delete(int data){        if(root == null) return;        BiNode node = root;//需要删除的节点        boolean left = true;        BiNode pre = node;//需要删除的节点的父节点        while(true){            if(node.data == data){                if(node.lchild == null && node.rchild == null){                    System.out.println("没有子节点");                    if(left) pre.lchild=null;                    else pre.rchild=null;                    return;                }else if(node.lchild!=null && node.rchild==null){                    System.out.println("只有左子节点");                    System.out.println("pre:"+pre.data);                    System.out.println("node:"+node.data);                    if(left){                        pre.lchild = node.lchild;                        node = null;                        return;                    }else{                        pre.rchild = node.lchild;                        node = null;                        return;                    }                }else if(node.lchild == null && node.rchild != null){                    System.out.println("只有右子节点");                    System.out.println("pre:"+pre.data);                    System.out.println("node:"+node.data);                    pre.rchild = node.rchild;                    node = null;                    return;                }else{                    System.out.println("左右子节点都有");                    BiNode lchild = node.rchild;//肯定不为null。                    pre = lchild;                    while(lchild.lchild != null){                        pre = lchild;                        lchild = lchild.lchild;                    }                    pre.lchild = null;                    node.data = lchild.data;                    return;                }            }else if(data > node.data){                pre = node;                node = node.rchild;                left = false;            }else{                pre = node;                 node = node.lchild;                left = true;            }        }    }    //查找    public BiNode find(int data){        if(root == null) return null;        BiNode node = root;        while(node!= null){            if(node.data == data){                return node;            }else if(data > node.data){                node = node.rchild;            }else{                node = node.lchild;            }        }        return null;    }    //前序遍历    public void preOrder(BiNode node){        if(node == null) return;        else{            System.out.print(node.data+" ");            preOrder(node.lchild);            preOrder(node.rchild);        }    }    //中序遍历    public void inOrder(BiNode node){        if(node == null) return;        else{            inOrder(node.lchild);            System.out.print(node.data+" ");            inOrder(node.rchild);        }    }    //后序遍历    public void postOrder(BiNode node){        if(node == null) return;        else{            postOrder(node.lchild);            postOrder(node.rchild);            System.out.print(node.data+" ");        }    }    static class BiNode {        int data;        BiNode lchild;        BiNode rchild;        public BiNode(int data, BiNode lchild, BiNode rchild){            this.data = data;            this.lchild = lchild;            this.rchild = rchild;        }        /* (non-Javadoc)         * @see java.lang.Object#toString()         */        @Override        public String toString() {            return "BiNode [data=" + data + ", lchild=" + lchild + ", rchild=" + rchild + "]";        }    }    public static void main(String[] args) {        BiTree tree = new BiTree();        tree.insertNode(5);        tree.insertNode(2);        tree.insertNode(1);        tree.insertNode(4);        tree.insertNode(3);        tree.insertNode(7);        tree.insertNode(6);        tree.insertNode(9);        tree.insertNode(8);        System.out.print("前序遍历：");        tree.preOrder(tree.root);        System.out.println();        System.out.print("中序遍历：");        tree.inOrder(tree.root);        System.out.println();        System.out.print("后序遍历：");        tree.postOrder(tree.root);        System.out.println();        int i = 4;        System.out.println("删除数据为"+i+"的节点");        tree.delete(i);        System.out.print("前序遍历：");        tree.preOrder(tree.root);        System.out.println();        System.out.print("中序遍历：");        tree.inOrder(tree.root);        System.out.println();        System.out.print("后序遍历：");        tree.postOrder(tree.root);        System.out.println();        int j = 5;        System.out.println("查找数据为"+j+"的节点");        BiNode node = tree.find(j);        System.out.println(node);    }}
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