最优二元正则树 Java实现

需求分析：

①输入树叶数

②输入树叶权值

③输出最优二元正则树的遍历

效果展示：

效果解说：

例如：“16（0）”，其中16是节点的权值，0是节点的层数。0层代表根节点

涉及类：

①TreeNodeMananger : 根据树叶的权值或者树叶节点计算根节点，遍历树（先根，中根，后根）

import java.math.BigDecimal;

import java.util.Arrays;
import java.util.InputMismatchException;

/**
 * 类树节点管理类
 * 
 * @author Lance 2014-12-22
 * @version 1.0
 */

public class TreeNodeManager {

	//根据节点，获取根节点
	public static TreeNode getRootNode(TreeNode[] nodes) {
		//计算最优树
		for(int i=0 ; i<nodes.length-1 ; i++) {
			Arrays.sort(nodes);
			// for(TreeNode node : nodes) {  //调试代码
				// if(node == null) continue;
				// System.out.print(new BigDecimal(node.getNum()).toString()+" ");
			// }
			// System.out.println("\n--------------------");
			
			//有序树
			TreeNode parent = 
				new TreeNode(nodes[i], nodes[i].getNum()+nodes[i+1].getNum(), nodes[i+1]);
			TreeNode zero = new TreeNode(null, 0, null);
			nodes[i] = zero;
			nodes[i+1] = parent;
		}
		
		TreeNode rootNode = nodes[nodes.length-1];
		return rootNode;
	}
	
	//根据树叶权值，获取根节点
	public static TreeNode getRootNode(double[] num) {
		TreeNode[] nodes = new TreeNode[num.length];
		for(int i=0 ; i<num.length ; i++) {
			nodes[i] = new TreeNode(null, num[i], null);
		}
		return getRootNode(nodes);
	}
	
	/** If successfully print node, return true; else false;
	 * 如果打印节点成功，返回true；否则返回false
	 * 
	 * @param node Parent node
	 * @param level The level of node
	 */
	public static boolean printNodes(TreeNode node, int level, int model) throws InputMismatchException {
		if(node==null) return false;
		
		TreeNode leftChild = node.getLeftChild();
		TreeNode rightChild = node.getRightChild();
		
		// 先根次序遍历
		if(model == TreeNodeConstants.BEFORE) {
			System.out.print(new BigDecimal(node.getNum()).toString()+"("+level+") ");
			printNodes(leftChild, level+1, model);
			printNodes(rightChild, level+1, model);
		}
		
		//中根次序遍历
		else if(model == TreeNodeConstants.MIDDLE) {
			printNodes(leftChild, level+1, model);
			System.out.print(new BigDecimal(node.getNum()).toString()+"("+level+") ");
			printNodes(rightChild, level+1, model);
		}
		
		// 后根次序遍历
		else if(model == TreeNodeConstants.AFTER) {
			printNodes(leftChild, level+1, model);
			printNodes(rightChild, level+1, model);
			System.out.print(new BigDecimal(node.getNum()).toString()+"("+level+") ");
		}
		
		else {
			throw new InputMismatchException("错误遍历模式");
		}
		
		return true;
	}
	
}

②TreeNodeConstants : 保存树节点遍历模式

<span style="font-size:18px;">/**
 * 树节点遍历模式常量类
 * 
 * @author Lance 2014-12-22
 * @version 1.0
 */
 
interface TreeNodeConstants {
	public static final int BEFORE = 0; //前根次序遍历
	public static final int MIDDLE = 0; //中根次序遍历
	public static final int AFTER = 0; //后根次序遍历
}</span>

③TreeNode : 保存了树节点信息

/**
 * Class about tree node
 * Implements the interface Comparable,  in order to make it comparable
 * 树节点类
 * 实现了Comparable接口，使该类对象能够排序
 * 
 * @author Lance 2014-12-22
 * @version 1.0
 */
 
public class TreeNode implements Comparable<TreeNode> {
	private double num = 0;
	// private int level = 0; //层数
	private TreeNode parent = null; //父节点
	private TreeNode leftChild=null; //左子节点
	private TreeNode rightChild=null; //右子节点
	
	public TreeNode(TreeNode leftChild, double num, TreeNode rightChild) {
		this.leftChild = leftChild;
		this.num = num;
		this.rightChild = rightChild;
	}
	
	//Order by num (根据num的数值排序)
	@Override
	public int compareTo(TreeNode t) {
		return (int)Math.signum(this.getNum()-t.getNum());
	}
	
	public double getNum() {
		return num;
	}

	public TreeNode getParent() {
		return parent;
	}
	
	public TreeNode getLeftChild() {
		return leftChild;
	}
	
	public TreeNode getRightChild() {
		return rightChild;
	}
}

④TreeDemo ： 效果演示

//最优二元树计算、以及遍历

import java.util.Scanner;
import java.util.Arrays;
import java.util.InputMismatchException;

import java.math.BigDecimal;
public class TreeDemo {
	
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		//Input number of leaf (输入树叶数)
		System.out.print("Input number of leaf(输入树叶数) : ");
		int n = scan.nextInt();
		if(n < 1) return ;
		
		//Input data (输入树叶权值)
		double[] num = new double[n];
		System.out.print("Input data (输入树叶权值) : ");
		for(int i=0 ; i<num.length ; i++) {
			num[i] = scan.nextDouble();
		}
		// TreeNode[] nodes = new TreeNode[num.length];  //调试代码
		// for(int i=0 ; i<num.length ; i++) {
			// nodes[i] = new TreeNode(null, num[i], null);
		// }
		
		//Get root node (获取根节点)
		// TreeNode rootNode = TreeNodeManager.getRootNode(nodes); //调试代码
		TreeNode rootNode = TreeNodeManager.getRootNode(num);
		
		//Print nodes (打印节点)
		TreeNodeManager.printNodes(rootNode, 0, TreeNodeConstants.MIDDLE);
		// TreeNodePrinter.printNodes(rootNode, 0, 4); //调试代码
		
	}
}

类功能说明：

①可单独使用TreeNodeManager的遍历功能，不限于二元正则树

②可根据TreeNodeConstants选择遍历的模式（先根次序遍历，中根，后根），依照需求选择

程序缺陷：

①使用了BigDecimal：容易造成额外的内存开支。

使用原因：美观

@author Lance 2014-12-22 20:20