huffman编码 c#实现

  1 using System;
  2 using System.Collections.Generic;
  3 using System.ComponentModel;
  4 using System.Data;
  5 using System.Drawing;
  6 using System.Text;
  7 using System.Windows.Forms;
  8 using System.Collections.Specialized;
  9 namespace HuffmanCode
 10 {
 11     public partial class Form1 : Form
 12     {
 13         class Node                                 //霍夫曼樹節點結構
 14         {
 15             public char code;
 16             public uint prioirry;                           //保存權值
 17             public Node lchild;                           //左孩子指針
 18             public Node rchild;                           //右孩子指針
 19         }
 20         public Form1()
 21         {
 22             InitializeComponent();
 23 
 24         }
 25 
 26         private Dictionary<char, string> dictcode = new Dictionary<char, string>();
 27         private Node huffTree;
 28 
 29         private int comparisonNode(Node n1, Node n2)
 30         {
 31             return (int)(n1.prioirry - n2.prioirry);
 32         }
 33 
 34         private string encode(string str)
 35         {
 36             dictcode.Clear();
 37             huffTree = null;
 38             if (string.IsNullOrEmpty(str))
 39             {
 40                 return "";
 41             }
 42             Dictionary<char, uint> priorityQueue = new Dictionary<char, uint>();
 43 
 44             for (int i = 0; i < str.Length; i++)
 45             {
 46                 if (priorityQueue.ContainsKey(str[i]))
 47                 {
 48                     priorityQueue[str[i]]++;
 49                 }
 50                 else
 51                 {
 52                     priorityQueue.Add(str[i], 1);
 53                 }
 54             }
 55             List<Node> listpc = new List<Node>();
 56             foreach (var item in priorityQueue)
 57             {
 58                 listpc.Add(new Node() { prioirry = item.Value, lchild = null, rchild = null, code = item.Key });
 59             }
 60 
 61             listpc.Sort(comparisonNode);
 62 
 63             while (listpc.Count > 1)
 64             {
 65                 Node n = new Node();
 66                 n.prioirry = listpc[0].prioirry + listpc[1].prioirry;
 67                 n.lchild = listpc[0];
 68                 n.rchild = listpc[1];
 69                 listpc.RemoveAt(0);
 70                 listpc.RemoveAt(0);
 71                 int index = -1;
 72                 for (int i = 0; i < listpc.Count; i++)
 73                 {
 74                     if (n.prioirry <= listpc[i].prioirry)
 75                     {
 76                         index = i;
 77                         break;
 78                     }
 79                 }
 80                 if (index == -1) { index = listpc.Count; }
 81                 listpc.Insert(index, n);
 82             }
 83             string encodestr = "";
 84             viewTree(listpc[0], "");
 85             huffTree = listpc[0];
 86             for (int i = 0; i < str.Length; i++)
 87             {
 88                 encodestr += dictcode[str[i]];
 89             }
 90             return encodestr;
 91         }
 92 
 93 
 94         private void viewTree(Node n, string v)
 95         {
 96             if (n.code != '\0')
 97             {
 98                 dictcode.Add(n.code, v);
 99             }
100             else
101             {
102                 if (n.lchild != null)
103                 {
104                     string vl = v + "0";
105                     viewTree(n.lchild, vl);
106                 }
107                 if (n.rchild != null)
108                 {
109                     string vr = v + "1";
110                     viewTree(n.rchild, vr);
111                 }
112             }
113         }
114 
115         private string decode(string str)
116         {
117             Node root = huffTree;
118             string result = "";
119             for (int i = 0; i < str.Length; i++)
120             {
121                 if (root.code != '\0')
122                 {
123                     result += root.code.ToString();
124                     root = huffTree;
125                 }
126 
127                 if (str[i] == '0')
128                 {
129                     root = root.lchild;
130                 }
131                 else
132                 {
133                     root = root.rchild;
134                 }
135             }
136             if (root.code != '\0')
137             {
138                 result += root.code.ToString();
139             }
140             return result;
141         }
142 
143         private void button1_Click(object sender, EventArgs e)
144         {
145             textBox2.Text = encode(textBox1.Text);
146         }
147 
148         private void button2_Click(object sender, EventArgs e)
149         {
150             textBox3.Text = decode(textBox2.Text);
151         }
152     }
153 }