利用二叉树设计一款简单的huffman编码器

从磁盘读入一个仅包括英文字母及标点符号的文本文件(如f1.txt)，统计各字符的频度，据此构建huffman树，对各字符进行编码，并将字符集，频度集及相应编码码字集输出在显示器或保存在另一个文本文件（如 f1_code.txt）中.


思路：

Void HuffmanCode(HuffNode<char>* ht1, char * Code, int length)

{   ……

    若  ht1为空  return

    若  ht1  为叶子结点     打印（输出） ht1 的val， weight， Code；

    否则 如果 ht1 的左孩子不为空

             copy Code到一个临时字符串 temp_c,

             令 len=length;   len++;temp_c[len]= ‘0’ ;

             递归调用  huffmanCode( ht1->left(),  temp_c, len)

     否则 如果 ht1 的右孩子不为空

             copy Code到一个临时字符串temp_c,

             令 len=length;   len++;temp_c[len]= ‘1’ ;

             递归调用  huffmanCode( ht1->right(),  temp_c, len)

……

#include<iostream>

#include<fstream>

#define SIZELEAF 100

#define SIZENODE 2*SIZELEAF-1

#define MAXWEIGHT 10000

using namespace std;

 

typedef struct          //结构体 

{
int weight;
int lchild;
int rchild;
int parent;

}Node,*HuffmanTree;

typedef struct

{
char ch;
int codes[SIZELEAF];   
int num;

} Code;

void huftreenode (int weight[SIZELEAF],Node node[SIZENODE], int n)

{
int w1,w2,n1,n2,i,k;
for (i=0; i<2*n-1; i++)          //全部节点初始化 
{
node[i].weight=0;
node[i].lchild=0;
node[i].rchild=0;
node[i].parent=0;
}
for (i=0; i<n; i++)
{
node[i].weight=weight[i];
}

    for (i=0; i<n-1; i++)

    {

        w1=w2=MAXWEIGHT;    

        n1=n2=0;

        for (k=0; k<n+i; k++)

        {

            if (node[k].weight < w1 && node[k].parent==0)

            {

                w2=w1; 

                n2=n1; 

                w1=node[k].weight;

                n1=k;

            }

            else if (node[k].weight < w2 && node[k].parent==0)

            {

                w2=node[k].weight;

                n2=k;

            }

        } 

        node[n1].parent = n+i;

        node[n2].parent = n+i;

        node[n+i].weight = node[n1].weight + node[n2].weight;

        node[n+i].lchild = n1;

        node[n+i].rchild = n2;
}

}

void huftreecode (Code code[SIZENODE], Node node[SIZENODE], int n, char s[SIZELEAF])

{
int i,p,x,c;
for(i=0; i<n; i++)                      
{

code[i].ch=s[i];                            //回溯发，从叶子往上找，直到根 
p=node[i].parent;
x=i;

        c=0;
while( p != 0)
{
if(node[p].lchild == x)
{
code[i].codes[c]=0;
}
    else
{
    code[i].codes[c]=1;
}
c++;
x=p;
    p=node[x].parent;
}
code[i].num=c-1;
}

}

void input(char sen[SIZELEAF], int number[SIZELEAF], int *num)

{
int Num[SIZELEAF];
char sensus[SIZELEAF];
FILE *fp;
char ch;
int sort;
char filename[100];
int i,j,k,n,m;
for(i=0;i<SIZELEAF;i++)
{
Num[i]=0;
sensus[i]='0';
}
cout<<"Please input the file's name:\n";
gets(filename);

if((fp=fopen(filename,"r")) == NULL)
{
cout<<"\ncan not open the file!";
getchar();
exit(0);
}
*num=0;
while(ch!=EOF)
//统计字频，使用ASCII来统计 
{
ch=fgetc(fp);
//sensus0-9来存数字0-9；接下来存a-z,,...,,,,,
if(ch >='0' && ch <= '9')
{
sort=ch-'0';
Num[sort]++;
sensus[sort]=ch;
}
else if(ch >= 'A' && ch <='Z')
{
sort=ch-'A'+10;
Num[sort]++;
sensus[sort]=ch;
}
else if(ch >= 'a' && ch <='z')

{
sort=ch-'a'+36;
Num[sort]++;
sensus[sort]=ch;
}
else if(ch == ',')
{
Num[62]++;
sensus[62]=ch;
}
else if(ch == '.')
{
Num[63]++;
sensus[63]=ch;
}
else if(ch == '(')
{
Num[64]++;
sensus[64]=ch;
}
else if(ch == ')')
{
Num[65]++;
sensus[65]=ch;
}
else if(ch == '-')
{
Num[66]++;
sensus[66]=ch;
}
}
for(n=0;n<67;n++)
{
if(Num
!=0)
//清空 字符频度为
(*num)++;
}

for(m=0;m<67;m++)
{
number[m]=0;
sen[m]='0';
}
for(j=0,k=0;k<67;j++,k++)

{

while(Num[k] == 0)
k++;

number[j]=Num[k];
sen[j]=sensus[k];
}
cout<<"编码结果："<<endl; 
for(i=0;i<*num;i++)
{
cout<<sen[i]<<"\t";
cout<<number[i]<<"\t"<<endl;
}
fclose(fp);

}

int main()

{
int n;

    int i,j,x;
char sensus[SIZELEAF];
int Num[SIZELEAF];

Node hufnode[SIZENODE];
Code hufcode[SIZELEAF];
char choice;

cout<<"*******************************************************************\n";
cout<<"                      Huffman编码器\n";
cout<<endl;
cout<<"
author:**  **"<<endl; 
cout<<"*******************************************************************\n\n";
cout<<"输出说明：字符       字频\n";
cout<<"
  字符：     编码" <<endl; 
cout<<endl;

do
{
input(sensus,Num,&n);
huftreenode (Num,hufnode,n);
huftreecode (hufcode,hufnode,n,sensus);
for(i=0; i<n; i++)
{
cout<<hufcode[i].ch<<"  编码："<<"\t";
x=hufcode[i].num;
for(j=x; j>=0; j--)
{
cout<<hufcode[i].codes[j];
}
cout<<endl;
}
cout<<endl;
cout<<endl;
cout<<"是否继续(Y 继续) （N 退出）\n";
cin>>choice;
}
while(choice == 'Y');
}