哈夫曼树的实现
1.找到一个哈夫曼树的例子
import java.util.Scanner;
public class HuffmanCode{
//建立数的节点类
static class Node{
int weight;//频数
int parent;
int leftChild;
int rightChild;
public Node(int weight,int parent,int leftChild,int rightChild){
this.weight=weight;
this.parent=parent;
this.leftChild=leftChild;
this.rightChild=rightChild;
}
void setWeight(int weight){
this.weight=weight;
}
void setParent(int parent){
this.parent=parent;
}
void setLeftChild(int leftChild){
this.leftChild=leftChild;
}
void setRightChild(int rightChild){
this.rightChild=rightChild;
}
int getWeight(){
return weight;
}
int getParent(){
return parent;
}
int getLeftChild(){
return leftChild;
}
int getRightChild(){
return rightChild;
}
}
//新建哈夫曼编码
static class NodeCode{
String character;
String code;
NodeCode(String character,String code){
this.character=character;
this.code=code;
}
NodeCode(String code){
this.code= code;
}
void setCharacter(String character){
this.character=character;
}
void setCode(String code){
this.code=code;
}
String getCharacter(){
return character;
}
String getCode(){
return code;
}
}
//初始化一个huffuman树
public static void initHuffmanTree(Node[] huffmanTree,int m){
for(int i=0;i<m;i++){
huffmanTree[i] = new Node(0,-1,-1,-1);
}
}
//初始化一个huffmanCode
public static void initHuffmanCode(NodeCode[] huffmanCode,int n){
for(int i=0;i<n;i++){
huffmanCode[i]=new NodeCode("","");
}
}
//获取huffmanCode的符号
public static void getHuffmanCode(NodeCode[] huffmanCode , int n){
Scanner input = new Scanner(System.in);
for(int i=0;i<n;i++){
String temp = input.next();
huffmanCode[i] = new NodeCode(temp,"");
}
}
//获取huffman树节点频数
public static void getHuffmanWeight(Node[] huffmanTree , int n){
Scanner input = new Scanner(System.in);
for(int i=0;i<n;i++){
int temp = input.nextInt();
huffmanTree[i] = new Node(temp,-1,-1,-1);
}
}
//从n个结点中选取最小的两个结点
public static int[] selectMin(Node[] huffmanTree ,int n)
{
int min[] = new int[2];
class TempNode
{
int newWeight;//存储权
int place;//存储该结点所在的位置
TempNode(int newWeight,int place){
this.newWeight=newWeight;
this.place=place;
}
void setNewWeight(int newWeight){
this.newWeight=newWeight;
}
void setPlace(int place){
this.place=place;
}
int getNewWeight(){
return newWeight;
}
int getPlace(){
return place;
}
}
TempNode[] tempTree=new TempNode[n];
//将huffmanTree中没有双亲的结点存储到tempTree中
int i=0,j=0;
for(i=0;i<n;i++)
{
if(huffmanTree[i].getParent()==-1&& huffmanTree[i].getWeight()!=0)
{
tempTree[j]= new TempNode(huffmanTree[i].getWeight(),i);
j++;
}
}
int m1,m2;
m1=m2=0;
for(i=0;i<j;i++)
{
if(tempTree[i].getNewWeight()<tempTree[m1].getNewWeight())//此处不让取到相等，是因为结点中有相同权值的时候，m1取最前的
m1=i;
}
for(i=0;i<j;i++)
{
if(m1==m2)
m2++;//当m1在第一个位置的时候，m2向后移一位
if(tempTree[i].getNewWeight()<=tempTree[m2].getNewWeight()&& i!=m1)//此处取到相等，是让在结点中有相同的权值的时候，
//m2取最后的那个。
m2=i;
}
min[0]=tempTree[m1].getPlace();
min[1]=tempTree[m2].getPlace();
return min;
}
//创建huffmanTree
public static void createHaffmanTree(Node[] huffmanTree,int n){
if(n<=1)
System.out.println("Parameter Error!");
int m = 2*n-1;
//initHuffmanTree(huffmanTree,m);
for(int i=n;i<m;i++)
{
int[] min=selectMin(huffmanTree,i);
int min1=min[0];
int min2=min[1];
huffmanTree[min1].setParent(i);
huffmanTree[min2].setParent(i);
huffmanTree[i].setLeftChild(min1);
huffmanTree[i].setRightChild(min2);
huffmanTree[i].setWeight(huffmanTree[min1].getWeight()+ huffmanTree[min2].getWeight());
}
}
//创建huffmanCode
public static void createHaffmanCode(Node[] huffmanTree,NodeCode[] huffmanCode,int n){
Scanner input = new Scanner(System.in);
//只给了十个空？？？
char[] code = new char[30];
int start;
int c;
int parent;
int temp;
code[n-1]='0';
for(int i=0;i<n;i++)
{
StringBuffer stringBuffer = new StringBuffer();
start=n-1;
c=i;
while( (parent=huffmanTree[c].getParent()) >=0 )
{
start--;
code[start]=((huffmanTree[parent].getLeftChild()==c)?'0':'1');
c=parent;
}
for(;start<n-1;start++){
stringBuffer.append(code[start]);
}
huffmanCode[i].setCode(stringBuffer.toString());
}
}
//输出hufmanCode
public static void ouputHaffmanCode(NodeCode[] huffmanCode,int n){
System.out.println("字符与编码的对应关系如下：");
for(int i=0;i<n;i++){
System.out.println(huffmanCode[i].getCharacter()+":"+huffmanCode[i].getCode());
}
}
//主函数
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int n;
int m;
System.out.print("请输入字符个数：");
n = input.nextInt();
m=2*n-1;
Node[] huffmanTree = new Node[m];
NodeCode[] huffmanCode = new NodeCode[n];
//初始化huffmanTree,huffmanCode
initHuffmanTree(huffmanTree,m);
initHuffmanCode(huffmanCode,n);
//获取huffmanCode的符号
System.out.print("请输入哈夫曼编码的字符：");
getHuffmanCode(huffmanCode,n);
//获取huffmanTree的频数
System.out.print("请输入哈夫曼编码字符对应的频数：");
getHuffmanWeight(huffmanTree,n);
//创建huffmanTree
createHaffmanTree(huffmanTree,n);
//创建huffmanCode
createHaffmanCode(huffmanTree,huffmanCode,n);
//输出huffmanCode编码
ouputHaffmanCode(huffmanCode,n);
}
}
改造成我需要的哈夫曼树并添加所需功能
public int compareTo(HuffmanNode node) {
if (this.count >= node.count){
return 1;
}
else {
return -1;
}
}
public HuffmanNode createTree(List<HuffmanNode> nodes) {
while (nodes.size() > 1) {
Collections.sort(nodes);
HuffmanNode left = nodes.get(nodes.size() - 2);
left.setCode("0");
HuffmanNode right = nodes.get(nodes.size() - 1);
right.setCode("1");
HuffmanNode parent = new HuffmanNode(null, left.getLength() + right.getLength());
parent.setLeft(left);
parent.setRight(right);
nodes.remove(left);
nodes.remove(right);
nodes.add(parent);
}
return nodes.get(0);
}
public List<HuffmanNode> breadth(HuffmanNode root) {
List<HuffmanNode> list = new ArrayList<HuffmanNode>();
Queue<HuffmanNode> queue = new ArrayDeque<HuffmanNode>();
if (root != null) {
queue.offer(root);
root.getLeft().setCode(root.getCode() + "0");
root.getRight().setCode(root.getCode() + "1");
}
while (!queue.isEmpty()) {
list.add(queue.peek());
HuffmanNode node = queue.poll();
if (node.getLeft() != null)
node.getLeft().setCode(node.getCode() + "0");
if (node.getRight() != null)
node.getRight().setCode(node.getCode() + "1");
if (node.getLeft() != null) {
queue.offer(node.getLeft());
}
if (node.getRight() != null) {
queue.offer(node.getRight());
}
}
return list;
}
- 主函数
File file = new File("编码文件.txt");
if (!file.exists()) {
file.createNewFile();
}
BufferedReader br = new BufferedReader(new FileReader(file));
String s;
String message = "";
while((s = br.readLine()) != null){
message += s;
}
String[] result = message.split("");
for (int n = 0;n < result.length; n++){
for (int i = 0; i < 27; i++){
if (result[n].equals(list.get(i))){
number[i] += 1;
}
}
}
HuffmanTree huffmanTree = new HuffmanTree();
HuffmanNode node = huffmanTree.createTree(nodeList);
List<HuffmanNode> inlist = new ArrayList<HuffmanNode>();
inlist = huffmanTree.breadth(node);
String res = "";
for(int f = 0; f < sum; f++){
for(int j = 0;j<name.length;j++){
if(message.charAt(f) == name[j].charAt(0))
res += code[j];
}
}
String string2 = "";
for(int h = putlist.size(); h > 0; h--){
string1 = string1 + putlist.get(0);
putlist.remove(0);
for(int i=0;i<code.length;i++){
if (string1.equals(code[i])) {
string2 = string2+""+ name[i];
string1 = "";
}
}
}
运行结果
