1120 哈夫曼树的创建遍历查找当前节点的编码

来源：互联网发布：松下网络摄像机默认ip 编辑：程序博客网时间：2024/06/02 04:04
package com;import java.util.ArrayList;import java.util.Collections;import java.util.LinkedList;import java.util.Stack;/** * 类说明:  哈夫曼树的创建遍历查找当前节点的编码 */public class HaffmanTree {    TreeNode root;    /**     * @version 创建时间: 2017-11-21 下午8:57:01     * 类说明:声明一个类，     */    public static class TreeNode<T> implements Comparable<TreeNode<T>>{        T data;        int weight;        TreeNode leftChild;        TreeNode rightNode;        TreeNode parent;        public TreeNode(T data, int weight) {            super();            this.data = data;            this.weight = weight;            this.leftChild = null;            this.rightNode = null;            this.parent = null;        }        @Override        public int compareTo(TreeNode<T> o) {            //根据weight来排序            if(this.weight>o.weight){                return -1;            }else if(this.weight<o.weight){                return 1;            }            return 0;        }    }    /**     * 创建haffman树     * @param list     * @return     */    public TreeNode createHaffManTree(ArrayList<TreeNode> list){        while (list.size()>1) {            //取最小的两个值，构建新的节点，进行排序            Collections.sort(list);//从大到小排序            TreeNode leftNode=list.get(list.size()-1);//取最小的值            TreeNode rightNode=list.get(list.size()-2);//取第二小的值            TreeNode parent=new TreeNode("data", leftNode.weight+rightNode.weight);            parent.leftChild=leftNode;            parent.rightNode=rightNode;            leftNode.parent=parent;            rightNode.parent=parent;            list.remove(leftNode);            list.remove(rightNode);            list.add(parent);        }        //最终list里面只剩下一个元素        root=list.get(0);        return list.get(0);    }    /**     * 遍历哈夫曼树     * @param root     * 思路：循环     每次取parent，取出来后，添加leftChild  rightChild     */    public void showHaffman(TreeNode root){        LinkedList<TreeNode> list = new LinkedList<>();        ArrayList<TreeNode> arrayList = new ArrayList<>();        list.offer(root);//队列为空时候，使用add方法会报错，而offer方法会返回false,Queue使用时,才会采用 offer/poll/take等方法作为链表对象时,offer等方法相对来说没有什么意义这些方法是用于支持队列应用的。        while(!list.isEmpty()){            TreeNode node=list.pop();//取出栈顶元素            System.out.print(node.data+" ");            if(node.leftChild!=null){                list.offer(node.leftChild);            }            if(node.leftChild!=null){                list.offer(node.rightNode);            }        }    }    /**     * 获得当前的节点编码   （左子为0  右子为1）     * @param node     */    public void getCode(TreeNode node){        Stack<String> stack = new Stack<>();        TreeNode treeNode = node;        while(treeNode!=null && treeNode.parent !=null){            //left 0  right 1            if(treeNode.parent.leftChild == treeNode){                stack.push("0");            }else if(treeNode.parent.rightNode == treeNode){                stack.push("1");            }            treeNode=treeNode.parent;        }        while (!stack.isEmpty()) {            System.out.print(stack.pop());        }    }    public static void main(String[] args) {        ArrayList<TreeNode> list = new ArrayList<>();        TreeNode<String> node = new TreeNode("good", 54);        list.add(node);        list.add(new TreeNode("morning", 10));        list.add(new TreeNode("afternoon", 20));        list.add(new TreeNode("hello", 100));        list.add(new TreeNode("hi", 200));        HaffmanTree tree = new HaffmanTree();        tree.createHaffManTree(list);        tree.showHaffman(tree.root);        System.out.println();        tree.getCode(node);    }}
运行结果如下：
data data hi data hello data good morning afternoon
000
阅读全文
0 0