查找二叉树删除节点的操作

二叉查找树中，最复杂的操作就是删除操作。对于叶子节点，直接删除即可。对于一颗子树的节点，用子树取代原节点即可。对于拥有两颗子树的节点，首先用右子树最小的节点取代源节点，再递归删除此最小节点。

具体代码如下所示：

package com.Algorithm.Tree;import java.util.*;import java.io.*;/* * author:Tammy Pi * function:二叉查找树 */public class BiSearchTree {public TreeNode root=null;private Scanner scanner=null;public BiSearchTree(){scanner=new Scanner(System.in);}public TreeNode getRoot() {return root;}public void setRoot(TreeNode root) {this.root = root;}public Scanner getScanner() {return scanner;}public void setScanner(Scanner scanner) {this.scanner = scanner;}    public void createTree()    {    this.root=createTree(this.root);    }    public void midTraverse()    {    midTraverse(this.root);    }    //中序遍历，相当于排序    public void midTraverse(TreeNode root)    {    if(root!=null)    {    midTraverse(root.getLchild());    System.out.print(root.getData()+" ");    midTraverse(root.getRchild());    }    }//建立二叉查找树public TreeNode createTree(TreeNode root){String str=scanner.next();int n=Integer.parseInt(str);for(int i=0;i<n;i++){String data=scanner.next();if(root==null){root=new TreeNode(data);}else {TreeNode node=new TreeNode(data);TreeNode x=root,y=root;while(x!=null){if(x.getData().compareTo(node.getData())>0){y=x;x=x.getLchild();}else {y=x;x=x.getRchild();}}if(y.getData().compareTo(node.getData())>0){y.setLchild(node);}else{y.setRchild(node);}}}//for ireturn root;}//createTree//查找最小的节点public TreeNode findMin(TreeNode node){TreeNode x=node;while(node!=null){x=node;node=node.getLchild();}return x;}public void testRemove(){root.setRchild(remove(root.getRchild(),root.getRchild()));System.out.print("删除节点后，中序遍历结果为：");    midTraverse();}//删除节点//node为待删除节点public TreeNode remove(TreeNode node,TreeNode subTree){if(subTree==null){return null;}int state=node.getData().compareTo(subTree.getData());if(state<0){node.setLchild(remove(node,subTree.getLchild()));}else if(state>0){node.setRchild(remove(node,subTree.getRchild()));}else if(node.getLchild()!=null&&node.getRchild()!=null){TreeNode temp=findMin(node.getRchild());node.setData(temp.getData());node.setRchild(remove(temp,node.getRchild()));}else{node=(node.getLchild()!=null?node.getLchild():node.getRchild());}return node;}//用于测试的主函数public static void main(String[] args){BiSearchTree biTree=new BiSearchTree();biTree.createTree();System.out.println("查找二叉树建立完成！");System.out.print("中序遍历结果为：");biTree.midTraverse();System.out.println();biTree.testRemove();}}