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  • HuffmanTree(C#)

    HuffmanTree构造和编码
    1
    2  using System.Collections.Generic;
    3
    4
    5  namespace HuffmanCode
    6 {
    7 /// <summary>
    8 /// Huffman树结点
    9 /// </summary>
    10   public class Node
    11 {
    12 //字符
    13   public char Char;
    14 //计数
    15   public int Count;
    16 //二进制编码
    17   public string Code;
    18
    19 public Node Lchild;
    20 public Node Rchild;
    21 public Node Parent;
    22
    23 public Node()
    24 {
    25 Code = "";
    26 Char = '\0';
    27 Count = 0;
    28 Lchild = null;
    29 Rchild = null;
    30 Parent = null;
    31 }
    32 }
    33 /// <summary>
    34 /// 构造二叉树,叶子节点编码
    35 /// </summary>
    36   public class HuffmanTree
    37 {
    38 //HuffmanTree根结点
    39   public Node Root = new Node();
    40
    41 //构造HuffmanTree
    42 public void CreateHuffmanTree(List<Node> chlist)
    43 {
    44 while (chlist.Count > 2)
    45 {
    46 Node node1 = chlist[0];//Count最小结点;
    47 Node node2 = chlist[1];//Count次小结点
    48 Node node3 =new Node();
    49
    50 node3.Count = node1.Count + node2.Count;
    51
    52 node3.Lchild = node1;
    53 node1.Parent = node3;
    54 node1.Code = "0";//若为左结点,Code标记为0
    55
    56 node3.Rchild = node2;
    57 node2.Parent = node3;
    58 node2.Code = "1";//若为右结点,Code标记为0
    59
    60 //移除两个最小的结点,插入Count为两者之和的父结点
    61 chlist.RemoveAt(0);
    62 chlist.RemoveAt(0);
    63 chlist.Add(node3);
    64
    65 //对改动后的LIst按Count排序
    66 StaticMethod.Sort(chlist);
    67 }
    68 //退出whlie循环时List剩两个结点,则分别作为根结点的左右结点
    69 Root.Lchild = chlist[0];
    70 chlist[0].Parent = Root;
    71 chlist[0].Code = "0";
    72 Root.Rchild = chlist[1];
    73 chlist[1].Parent = Root;
    74 chlist[1].Code = "1";
    75 Root.Count = chlist[0].Count + chlist[1].Count;
    76 }
    77 //从叶子结点到根结点编码
    78 public List<Node> GoToRoot(List<Node> list)
    79 {
    80 Node pnode;
    81 foreach (Node node in list)
    82 {
    83 pnode = node;
    84 while (pnode.Parent!=null)
    85 {
    86 node.Code = pnode.Parent.Code + node.Code;
    87 pnode = pnode.Parent;
    88 }
    89 }
    90 return list;
    91 }
    92
    93 }//class HuffmanTree
    94 }
    95
    对文本中各字符出现频率进行统计
    using System;
    using System.Collections.Generic;
    using System.Text;
    using System.IO;


    namespace HuffmanCode
    {

    /// <summary>
    /// 对文本统计字符并计数,存入Chlist
    /// </summary>
    public class CharList
    {
    public static List<Node> ChList;

    public List<Node> List
    {
    get
    {
    return ChList;
    }
    set
    {
    ChList
    = value;
    }
    }

    public CharList()
    {
    ChList
    = new List<Node>();
    }

    public void Read()
    {
    string path = "text.txt";
    Encoding encoding
    = TxtFileEncoding.GetEncoding(path);
    Console.WriteLine(encoding);
    var sr
    = new StreamReader(path, encoding);

    while (!sr.EndOfStream)
    {
    Node node
    =new Node();
    node.Char
    = (char)sr.Read();
    node.Count
    = 1;
    int flag = 0;

    foreach (Node v in ChList)
    {
    if(v.Char==node.Char)
    {
    v.Count
    += 1;//若字符已入表,则计数
    flag = 1;
    break;
    }
    }
    //新字符入表,拒绝空格和回车和制表符
    if (flag == 0 && node.Char != '\x20' && node.Char != '\n' && node.Char != '\r')
    {
    ChList.Add(node);
    }
    }
    sr.Close();

    }
    }
    /// <summary>
    /// 对字符集按计数升序排序,显示字符集的静态方法
    /// </summary>
    public class StaticMethod
    {
    //升序
    public static int Compare(Node a , Node b)
    {
    if (a.Count<b.Count)
    return -1;
    if (a.Count==b.Count)
    return 0;

    return 1;
    }

    public static void Sort(List<Node> list)
    {
    list.Sort(
    new Comparison<Node>(Compare));
    }
    //打印字符集
    public static void Display( List<Node> list)
    {

    for (int i = 0; i < list.Count;i++ )
    {
    if (list[i].Char>128)
    {
    Console.Write(
    "字符:" + list[i].Char + " 计数:");
    }
    else
    {
    Console.Write(
    "字符:" + list[i].Char + " 计数:");
    }

    Console.Write(
    "{0,4}", list[i].Count);
    Console.Write(
    " 编码: ");
    Console.Write(
    "{0,-20}", list[i].Code); Console.WriteLine();
    }

    }
    }


    }
    StreamReader
    1 using System;
    2 using System.Text;
    3 using System.IO;
    4
    5 namespace HuffmanCode
    6 {
    7 ///
    8 /// 用于取得一个文本文件的编码方式(Encoding)。
    9 ///
    10 public class TxtFileEncoding
    11 {
    12 /// <summary>
    13 /// 取得一个文本文件的编码方式。如果无法在文件头部找到有效的前导符,Encoding.Default将被返回。
    14 /// </summary>
    15 /// <param name="fileName">文件名。</param>
    16 /// <returns></returns>
    17 public static Encoding GetEncoding(string fileName)
    18 {
    19 return GetEncoding(fileName, Encoding.Default);
    20 }
    21
    22 /// <summary>
    23 /// 取得一个文本文件流的编码方式。
    24 /// </summary>
    25 /// <param name="stream">文本文件流。</param>
    26 /// <returns></returns>
    27 public static Encoding GetEncoding(FileStream stream)
    28 {
    29 return GetEncoding(stream, Encoding.Default);
    30 }
    31
    32 /// <summary>
    33 /// 取得一个文本文件的编码方式。
    34 /// </summary>
    35 /// <param name="fileName">文件名。</param>
    36 /// <param name="defaultEncoding">默认编码方式。当该方法无法从文件的头部取得有效的前导符时,将返回该编码方式。 </param>
    37 /// <returns></returns>
    38 public static Encoding GetEncoding(string fileName, Encoding defaultEncoding)
    39 {
    40 FileStream fs = new FileStream(fileName, FileMode.Open);
    41 Encoding targetEncoding = GetEncoding(fs, defaultEncoding);
    42 fs.Close();
    43 return targetEncoding;
    44 }
    45
    46 /// <summary>
    47 /// 取得一个文本文件流的编码方式。
    48 /// </summary>
    49 /// <param name="stream">文本文件流。 </param>
    50 /// <param name="defaultEncoding">默认编码方式。当该方法无法从文件的头部取得有效的前导符时,将返回该编码方式。 </param>
    51 /// <returns></returns>
    52 public static Encoding GetEncoding(FileStream stream, Encoding defaultEncoding)
    53 {
    54 Encoding targetEncoding = defaultEncoding;
    55 if (stream != null && stream.Length >= 2)
    56 {
    57 //保存文件流的前4个字节
    58 byte byte1 = 0;
    59 byte byte2 = 0;
    60 byte byte3 = 0;
    61 byte byte4 = 0;
    62 //保存当前Seek位置
    63 long origPos = stream.Seek(0, SeekOrigin.Begin);
    64 stream.Seek(0, SeekOrigin.Begin);
    65
    66 int nByte = stream.ReadByte();
    67 byte1 = Convert.ToByte(nByte);
    68 byte2 = Convert.ToByte(stream.ReadByte());
    69 if (stream.Length >= 3)
    70 {
    71 byte3 = Convert.ToByte(stream.ReadByte());
    72 }
    73 if (stream.Length >= 4)
    74 {
    75 byte4 = Convert.ToByte(stream.ReadByte());
    76 }
    77 //根据文件流的前4个字节判断Encoding
    78 //Unicode {0xFF, 0xFE};
    79 //BE-Unicode {0xFE, 0xFF};
    80 //UTF8 = {0xEF, 0xBB, 0xBF};
    81 if (byte1 == 0xFE && byte2 == 0xFF)//UnicodeBe
    82 {
    83 targetEncoding = Encoding.BigEndianUnicode;
    84 }
    85 if (byte1 == 0xFF && byte2 == 0xFE && byte3 != 0xFF)//Unicode
    86 {
    87 targetEncoding = Encoding.Unicode;
    88 }
    89 if (byte1 == 0xEF && byte2 == 0xBB && byte3 == 0xBF)//UTF8
    90 {
    91 targetEncoding = Encoding.UTF8;
    92 }
    93 //恢复Seek位置
    94 stream.Seek(origPos, SeekOrigin.Begin);
    95 }
    96 return targetEncoding;
    97 }
    98 }
    99
    100 }
    101
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  • 原文地址:https://www.cnblogs.com/zhaos/p/1937034.html
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