java用三叉链表构建二叉树,二叉树的三叉链表存储及其Java实现

java用三叉链表构建二叉树,二叉树的三叉链表存储及其Java实现

三叉链表存储的思想是让每个节点持有三个引用parent、left、right，分别指向其父节点、左子节点和右子节点。如下图所示：

因此，三叉链表存储的节点大致如：

class Node{

T data;

Node parent;

Node left;

Node right;

}Java实现代码：

package com.liuhao.DataStructures;

import com.liuhao.DataStructures.TwoLinkBinTree.TreeNode;

public class ThreeLinkBinTree {

public static class TreeNode{

Object data;

TreeNode parent;

TreeNode left;

TreeNode right;

public TreeNode() {

}

public TreeNode(Object data) {

this.data = data;

}

public TreeNode(Object data, TreeNode parent, TreeNode left,

TreeNode right) {

this.data = data;

this.parent = parent;

this.left = left;

this.right = right;

}

}

private TreeNode root;

public ThreeLinkBinTree(){

< = new TreeNode();

}

//以指定元素创建

public ThreeLinkBinTree(E data){

< = new TreeNode(data);

}

/**

* 为指定节点添加子节点

* @param parent 待添加的节点

* @param data 添加子节点的数据

* @param isLeft 是否要添加左子节点

* @return 新增的节点

*/

public TreeNode addNode(TreeNode parent, E data, boolean isLeft){

if(parent == null){

throw new RuntimeException(parent + "节点为空，不能添加子节点！");

}

if(isLeft && parent.left != null){

throw new RuntimeException(parent + "节点已有左子节点，不能添加左子节点！");

}

if(!isLeft && parent.right != null){

throw new RuntimeException(parent + "节点已有右子节点，不能添加右子节点！");

}

TreeNode newNode = new TreeNode(data);

if(isLeft){

parent.left = newNode;

}else{

parent.right = newNode;

}

//让新节点的parent引用指向parent节点

newNode.parent = parent;

return newNode;

}

//判断二叉树是否为空

public boolean isEmpty(){

return root.data == null;

}

//获取根节点

public TreeNode getRoot(){

if(isEmpty()){

throw new RuntimeException("树为空，无法获取根节点！");

}

return root;

}

//获取指定节点的父节点

public TreeNode getParent(TreeNode node){

if(node == null){

throw new RuntimeException("节点为空，无法获取父节点！");

}

if(root == node){

throw new RuntimeException("根节点无法获取父节点！");

}

return node.parent;

}

//获取指定节点的左子节点

public TreeNode getLeft(TreeNode parent){

if(parent == null){

throw new RuntimeException(parent + "节点为空，不能获取子节点！");

}

return parent.left == null ? null : parent.left;

}

//获取指定节点的右子节点

public TreeNode getRight(TreeNode parent){

if(parent == null){

throw new RuntimeException(parent + "节点为空，不能获取子节点！");

}

return parent.right == null ? null : parent.right;

}

//获取指定节点的深度

private int getDeep(TreeNode node){

if(node == null){

return 0;

}

if(node.left == null && node.right == null){

return 1;

}else{

int leftDeep = getDeep(node.left);

int rightDeep = getDeep(node.right);

int max = leftDeep > rightDeep ? leftDeep : rightDeep;

return max + 1;

}

}

public int getTreeDeep(){

Deep(root);

}

}从上面的代码可以看出，三叉链表存储只是对而二叉链表的改进，通过增加一个parent的引用，可以让每个节点都能方便地访问其父节点。