Huffman树的编码译码

  1 #ifndef HUFFMAN_H_INCLUDED
  2 #define HUFFMAN_H_INCLUDED
  3 #include <iostream>
  4 #include <stdlib.h>
  5 #include <string>
  6 
  7 #define leafNumber 20
  8 #define totalNumber 39
  9 #define maxValue 100
 10 using namespace std;
 11 
 12 //权值类型, 这里定义为int
 13 typedef int WType;
 14 
 15 //树的结点类型, 这里定义为char, 表示字符
 16 typedef char TElemType;
 17 
 18 //Huffman树结点信息定义
 19 typedef struct HuffmanNode{
 20     TElemType data;
 21     WType weight;
 22     int left_child;
 23     int right_child;
 24     int parent;
 25     string code;    //每个结点的编码, 定义为 string 类
 26 };
 27 
 28 //Huffman树结构定义
 29 typedef struct HuffmanTree{
 30     HuffmanNode elem[totalNumber];
 31     int currentNumber;
 32 };
 33 
 34 /*
 35 *构建Huffman树
 36 */
 37 void createHuffmanTree( HuffmanTree &HT, WType w[], int n ) {
 38     int i, j, p1, p2, min1, min2;
 39     for( i = 0; i < n; i++ ) HT.elem[i].weight = w[i];
 40     for( i = 0; i < 2 * n - 1; i++ )
 41         HT.elem[i].parent = HT.elem[i].left_child = HT.elem[i].right_child = -1;
 42     for( i = n; i < 2 * n - 1; i++ ) {
 43         min1 = min2 = maxValue;
 44         for( j = 0; j < i; j++ ) {
 45             if( HT.elem[j].parent == -1 )
 46                 if( HT.elem[j].weight < min1 ) {
 47                     p2 = p1;
 48                     min2 = min1;
 49                     p1 = j;
 50                     min1 = HT.elem[j].weight;
 51                 }
 52                 else if( HT.elem[j].weight < min2 ) {
 53                     p2 = j;
 54                     min2 = HT.elem[j].weight;
 55                 }
 56         }
 57         HT.elem[i].left_child = p1;
 58         HT.elem[i].right_child = p2;
 59         HT.elem[i].weight = HT.elem[p1].weight + HT.elem[p2].weight;
 60         HT.elem[p1].parent = HT.elem[p2].parent = i;
 61     }
 62     HT.currentNumber = 2 * n - 1;
 63 }
 64 
 65 /*
 66 *对Huffman树每个结点进行编码
 67 */
 68 void Coding( HuffmanTree &HT, int n ) {
 69 
 70     //当前节点下标
 71             int current = 0;
 72             //父节点下标
 73             int parent = 0;
 74     for( int i = 2 * n - 2 ; i >= 0; i-- ) {
 75 
 76         current = i;
 77         parent = HT.elem[current].parent;
 78         /*
 79         if( parent == -1 ) HT.elem[current].code[0] = ‘0‘;
 80         else {
 81             if( HT.elem[parent].left_child == current ) {
 82                 strcat( HT.elem[current].code, HT.elem[parent].code );
 83                 strcat( HT.elem[current].code, "0" );
 84             }
 85             if( HT.elem[parent].right_child == current ) {
 86                 strcat( HT.elem[current].code, HT.elem[parent].code );
 87                 strcat( HT.elem[current].code, "1" );
 88             }
 89         }
 90         */
 91 
 92 
 93         while (parent != -1)
 94                 {
 95                     if (HT.elem[parent].left_child == current) HT.elem[i].code += "0";
 96                     else HT.elem[i].code += "1";
 97 
 98                     current = parent;
 99                     parent = HT.elem[current].parent;
100                 }
101 
102         //HT.elem[current].code += "0";
103         reverse( HT.elem[i].code.begin(), HT.elem[i].code.end() );
104 
105     }
106 
107 }
108 
109 /*
110 *译码
111 */
112 void decode( HuffmanTree &HT, int n ) {
113     cout << "输入电文: ";
114     char ch[100];
115     gets( ch );
116 
117     int i = 0;
118     int parent;
119     int root = 2 * n - 2;
120     int index = root;
121     int count = 0;
122     int len = strlen( ch );
123     while( ch[i] != ‘#‘ ) {
124         if( ch[i] == ‘0‘ ) {
125             index = HT.elem[index].left_child;
126             //cout << "经过0" << endl;
127             //cout << index << endl;
128             //count++;
129         }
130         else if( ch[i] == ‘1‘ ) {
131             index = HT.elem[index].right_child;
132             //cout << "经过1" << endl;
133             //cout << index << endl;
134             //count++;
135         }
136         if( HT.elem[index].left_child == -1 && HT.elem[index].right_child == -1 ) {
137             cout << HT.elem[index].data;
138             index = root;
139             //i += count;
140             //count = 0;
141             //cout << index << endl;
142         }
143         i++;
144     }
145 }
146 /*
147 *遍历
148 */
149 void PreOrder( HuffmanTree &HT, int n ) {
150     for( int i = 0; i < n; i++ ) {
151         cout << "字符: " << HT.elem[i].data << ", " << "权值: " << HT.elem[i].weight << "  Huffman编码: " << HT.elem[i].code << endl;
152     }
153 };
154 
155 
156 #endif // HUFFMAN_H_INCLUDED

#include "Huffman.h"
int main() {
    HuffmanTree HT;
    HT.elem[0].data = ‘A‘;
    HT.elem[1].data = ‘B‘;
    HT.elem[2].data = ‘C‘;
    HT.elem[3].data = ‘D‘;
    HT.elem[4].data = ‘E‘;
    WType weight[] = { 7, 5, 2, 4, 6 };
    //WType weight[] = { 5,7,2,13 };
    createHuffmanTree( HT, weight, 5 );
    Coding( HT, 5 );
    PreOrder( HT, 5 );

    cout << endl << endl;
    for( int i = 0; i < 9; i++ )
        cout << "Node " << i << " Code: " << HT.elem[i].code << endl;

    cout << endl << endl;
    for( int i = 0; i < 9; i++ ) {
        cout << "Node " << i << ": " << "weight = " << HT.elem[i].weight << ", parent = " << HT.elem[i].parent << ", left_child = " << HT.elem[i].left_child
                << ", right_child = " << HT.elem[i].right_child << endl;
    }
    decode( HT, 5 );
    return 0;
}