2021-06-17
作者:互联网
学习目标:
Huffman 编码 (节点定义与文件读取)
具体步骤:
1、 定义了一个内嵌类。
2、定义不同节点的内容包括: 字符 (仅对叶节点有效)、权重 (用的整数, 该字符的个数)、指向子节点父节点的引用。
3、NUM_CHARS 是指 ASCII 字符集的字符个数. 为方便起见, 仅支持 ASCII。
代码编写:
package datastructure.tree;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.stream.Collectors;
/**
* Huffman tree, encoding, and decoding. For simplicity, only ASCII characters
* are supported.
*
* @author Fan Min minfanphd@163.com.
*/
public class Huffman {
/**
* An inner class for Huffman nodes.
*/
class HuffmanNode {
/**
* The char. Only valid for leaf nodes.
*/
char character;
/**
* Weight. It can also be double.
*/
int weight;
/**
* The left child.
*/
HuffmanNode leftChild;
/**
* The right child.
*/
HuffmanNode rightChild;
/**
* The parent. It helps constructing the Huffman code of each character.
*/
HuffmanNode parent;
/**
*******************
* The first constructor
*******************
*/
public HuffmanNode(char paraCharacter, int paraWeight, HuffmanNode paraLeftChild,
HuffmanNode paraRightChild, HuffmanNode paraParent) {
character = paraCharacter;
weight = paraWeight;
leftChild = paraLeftChild;
rightChild = paraRightChild;
parent = paraParent;
}// Of HuffmanNode
/**
*******************
* To string.
*******************
*/
public String toString() {
String resultString = "(" + character + ", " + weight + ")";
return resultString;
}// Of toString
}// Of class HuffmanNode
/**
* The number of characters. 256 for ASCII.
*/
public static final int NUM_CHARS = 256;
/**
* The input text. It is stored in a string for simplicity.
*/
String inputText;
/**
* The length of the alphabet, also the number of leaves.
*/
int alphabetLength;
/**
* The alphabet.
*/
char[] alphabet;
/**
* The count of chars. The length is 2 * alphabetLength - 1 to include
* non-leaf nodes.
*/
int[] charCounts;
/**
* The mapping of chars to the indices in the alphabet.
*/
int[] charMapping;
/**
* Codes for each char in the alphabet. It should have the same length as
* alphabet.
*/
String[] huffmanCodes;
/**
* All nodes. The last node is the root.
*/
HuffmanNode[] nodes;
/**
*********************
* The first constructor.
*
* @param paraFilename
* The text filename.
*********************
*/
public Huffman(String paraFilename) {
charMapping = new int[NUM_CHARS];
readText(paraFilename);
}// Of the first constructor
/**
*********************
* Read text.
*
* @param paraFilename
* The text filename.
*********************
*/
public void readText(String paraFilename) {
try {
inputText = Files.newBufferedReader(Paths.get(paraFilename), StandardCharsets.UTF_8)
.lines().collect(Collectors.joining("\n"));
} catch (Exception ee) {
System.out.println(ee);
System.exit(0);
} // Of try
System.out.println("The text is:\r\n" + inputText);
}// Of readText
学习时间:
提示:这里可以添加计划学习的时间
例如:
1、 周一至周五晚上 7 点—晚上9点
2、 周六上午 9 点-上午 11 点
3、 周日下午 3 点-下午 6 点
学习产出:
提示:这里统计学习计划的总量
例如:
1、 技术笔记 2 遍
2、CSDN 技术博客 3 篇
3、 学习的 vlog 视频 1 个
标签:06,String,17,int,alphabet,paraFilename,2021,HuffmanNode,public 来源: https://blog.csdn.net/a1025976860/article/details/117992656