huffman树和huffman编码

//huffman树和huffman编码 #include <stdlib.h>
#include <iostream.h>
#include <stdio.h>
#include <string.h>

#define  OVERFLOW -1

typedef struct
{  
  char letter;
  int weight;
  int parent;
  int lchild;
  int rchild;
}HTNode,*HuffmanTree;

typedef char * *HuffmanCode;

void Select(HuffmanTree &HT,int i,int &s1,int &s2)
{
 /*选择森林中，根结点的权值最小和次小的两个树，
 *将其根结点的下标号记入s1和s2中
 */
 int j, k;
 for(k = 1; k < i; k++)
 {
  if(HT[k].parent != NULL)
   continue;
  s1 = k;/*init the number*/
  break;
 }
 for(j = 1; j < i; j++)
 {
  if(HT[j].parent != NULL)
   continue;
  if(HT[j].weight < HT[s1].weight)
   s1 = j;
 }
 for(k = 1; k <= i; k++)
 {
  if(HT[k].parent != NULL || k == s1)
   continue;
  s2 = k;
  break;
 }

 for(j = 1; j < i; j++)
 {
  if(HT[j].parent != NULL)
   continue;
  if(HT[j].weight <= HT[s2].weight && j != s1)
   s2 = j;
 } 

}

void  HuffmanCoding(HuffmanTree &HT,HuffmanCode &HC,char *zi,int *w,int n)
{
 HuffmanTree p;

 int m,i,s1,s2,f,c;
 int Istart = 1;
 char *cd;
 if(n <= 1)
  return;
 m = 2*n-1;
 if(!(HT=(HuffmanTree)malloc((m+1)*sizeof(HTNode))))
  exit(OVERFLOW);
 for(p=HT+1,i=1;i<=n;++i,++zi,++p,++w)
 {
 /*生成独立的森林*/
  p->parent = NULL;
  p->letter = *zi;
  p->lchild = NULL;
  p->rchild = NULL;
  p->weight = *w;
 }

 for(;i<=m;++i,++p)
 {
  (*p).weight=0;
  (*p).parent=0;
  (*p).lchild=0;
  (*p).rchild=0;
 }

 for(i=n+1;i<=m;++i)
 {
  Select(HT,i-1,s1,s2);
  HT[s1].parent=i;
  HT[s2].parent=i;
  HT[i].lchild=s1;
  HT[i].rchild=s2;
  HT[i].weight=HT[s1].weight+HT[s2].weight;
 }
 HC=(HuffmanCode)malloc((n+1)*sizeof(char *));
 cd=(char*)malloc(n*sizeof(char));/*临时的code存储*/
 cd[n-1]='\0';
 for(i=1;i<=n;++i)
 {
   Istart = n - 1;
  /*按已生成的哈夫曼树，得到各个字符的哈夫曼编码
  */
 
   for(c = i, f = HT[i].parent; f != 0; c = f, f = HT[f].parent)
    if(HT[f].lchild == c)
     cd[--Istart] = '0';
    else
     cd[--Istart] = '1';
   HC[i] = (char *)malloc((n - Istart) * sizeof(char));
   strcpy(HC[i], &cd[Istart]);
   
 }
  free(cd);
 }
void main()
{
 HuffmanTree HT;
 HuffmanCode HC;
 int i,j,yu;
 char zi[9]={'A','B','C','D','E','F','G','H'};
 int w[100];
 char z;
 char c[100];
 z='A';
 cout<<endl;
 for(i=0;i<=7;i++)
 {
  cout<<"please input the weight for "<<z<<":";
  cin>>w[i];
  z++;
 }
 HuffmanCoding(HT,HC,zi,w,8);
 cout<<endl;
 cout<<"char          weight         huffmancode    "<<endl;
 for(i=1;i<=8;i++)
  cout<<HT[i].letter<<"  "<<HT[i].weight<<"  "<<HC[i]<<endl;
 cout<<"please input the text:";
 cin>>c;
 cout<<"The  code   is:";
 
 for(i=0; i < strlen(c);  i++)
  /*根据字符的哈夫曼编码，将输入的文本（变量c表示的）翻译成电码。 
  */
  cout<<HC[(c[i] - 'A' + 1)];

       cout<<endl;
       cout<<"Enter the code:";
       cin>>c;
       j=strlen(c);
       yu=15;
       i=1;
       cout<<"The text is:";
       while(i <= j)
       {
        while(HT[yu].lchild != 0)/*因为是完全二叉树*/
        {
   if(c[i-1] == '0')
   {
   /*用哈夫曼树，将输入的电码（变量c表示的）翻译成文本，
   说明：变量名c在程序中    
   */
    yu = HT[yu].lchild;
    i++;
    continue;
   }
   if(c[i-1]== '1')
   {
    yu=HT[yu].rchild;
    i++;
    continue;
   }
  }
  /*显示由部分电码译码得到的字符，并准备对后面的电码进行译码*/
        cout<<HT[yu].letter;
        yu = 15;
 }
       cout<<endl;
} //没有出错处理

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