哈弗曼树及其操作

 1 package com.neusoft.Tree;
 2 
 3 public class HuffmanNode {
 4     public int weight;
 5     //加入哈夫曼树的标志，flag=0表示该节点没有加入哈夫曼树，=1表示加入
 6     public int flag;
 7     public HuffmanNode parent,lchild,rchild;
 8     public HuffmanNode() {
 9         this(0);
10     }
11     public HuffmanNode(int weight){
12         this.weight=weight;
13         flag=0;
14         parent=lchild=rchild=null;
15     }
16 }

 1 package com.neusoft.Tree;
 2 /**
 3  * @author zhao-chj
 4  * 哈夫曼树及其操作
 5  */
 6 public class HuffmanTree {
 7     
 8     //求哈夫曼编码的算法，w存放n个字符的权值
 9     public int[][] huffmanCoding (int[] w){
10         int n= w.length;//哈夫曼树的字符个数
11         int m=2*n-1;//哈夫曼树的节点个数
12         HuffmanNode[] HN =new HuffmanNode[m];
13         int i=0;
14         for (i = 0;  i< n; i++) {
15             HN[i] = new HuffmanNode(w[i]);//构造n个具有权值的节点
16         }
17         for (i = n;  i< m; i++) {
18             HuffmanNode min1=selectMin(HN,i-1);
19             min1.flag=1;//表示已标记
20             HuffmanNode min2=selectMin(HN, i-1);
21             min2.flag=1;
22             //构造min1和min2的父节点，并且修改权值
23             HN[i] =new HuffmanNode();
24             min1.parent=HN[i];
25             min2.parent=HN[i];
26             HN[i].lchild=min1;
27             HN[i].rchild=min2;
28             HN[i].weight=min1.weight+min2.weight;
29         }
30         //从叶子节点到根逆向求每个字符的哈夫曼编码
31         int[][] HuffCode =new int[n][n];//分配n个字符编码存储空间
32         for (int j = 0; j <n; j++) {
33             int start=n-1;//编码的开始位置，初始化为数组的结尾
34             for (HuffmanNode c=HN[j],p=c.parent; p!=null; c=p,p=p.parent) {
35                 //从叶子结点到根逆向求解编码
36                 if (p.lchild.equals(c)) {//左孩子编码为0
37                     HuffCode[j][start--] =0;
38                 }else {
39                     //右孩子编码为1
40                     HuffCode[j][start--]=1;
41                 }
42                 HuffCode[j][start]=-1;//编码的开始标志为-1
43             }
44         }
45         return HuffCode;
46     }
47     /**
48      * 在HN[0...i-1]选择不再哈夫曼树中且weight最小的节点
49      */
50     private HuffmanNode selectMin(HuffmanNode[] HN, int end) {
51         HuffmanNode min=HN[end];
52         for (int i = 0; i < end; i++) {
53             HuffmanNode h=HN[i];
54             if (h.flag==0&&h.weight<min.weight) {
55                 //不再哈夫曼树中且weight最小的节点
56                 min=h;
57             }
58         }
59         return min;
60     }
61     public static void main(String[] args) {
62         int [] w={23,11,5,3,29,14,7,8};
63         HuffmanTree T =new HuffmanTree();//构造哈夫曼树
64         int [][] HN=T.huffmanCoding(w);//求哈夫曼编码
65         System.out.println("哈夫曼编码为：");
66         for (int i = 0; i < HN.length; i++) {
67             System.out.print(w[i]+" ");
68             for (int j = 0; j < HN[i].length; j++) {
69                 if (HN[i][j] ==-1 ) {//数组结尾标志
70                     for (int k = j+1; k < HN[i].length; k++) {
71                         System.out.print(HN[i][k]);
72                     }
73                     break;
74                 }
75             }
76             System.out.println();
77         }
78     }
79 }