数据结构——赫夫曼编码

效果如下：



  源程序如下：

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

typedef struct

{

  int weight;

  int parent,lchild,rchild;

}HTNode,*HuffmanTree;      //动态分配数组存储赫夫曼树

typedef char **HuffmanCode;//动态分配数组存储赫夫曼编码表

void Select(HuffmanTree HT,int n,int &s1,int &s2)

{
int i;
s1=s2=0;
for(i=1;i<=n;i++)
{
if(HT[i].weight<HT[s2].weight&&HT[i].parent==0&&s2!=0)
{
if(HT[i].weight<HT[s1].weight)
{
s2=s1;
s1=i;
}
else
s2=i;
}
if((s1==0||s2==0)&&HT[i].parent==0)
{
if(s1==0)
s1=i;
else if(s2==0)
{
if(HT[i].weight<HT[s1].weight)
{
s2=s1;s1=i;
}
else
s2=i;
}
}

}
if(s1>s2)
{
i=s1;
s1=s2;
s2=i;
}

}

void HuffmanCoding(HuffmanTree &HT,HuffmanCode &HC,int *w,int n)

{
int i,m,start,c,f;
int s1=0,s2=0;
char *cd;
HuffmanTree p;
if(n<=1) 
return;
m=2*n-1;
HT=(HuffmanTree)malloc((m+1)*sizeof(HTNode));//0号单元未用
for(p=HT+1,i=1;i<=n;++i,++p,++w)
{
 p->weight=*w;
 p->parent=0;
 p->lchild=0;
 p->rchild=0;
}
for(;i<=m;++i,++p)
{
 p->weight=0;
 p->parent=0;
 p->lchild=0;
 p->rchild=0;
}
for(i=n+1;i<=m;++i)//建赫夫曼树
{
//----在HT[1...i-1]选择parent为0且weight最小的两个接点，其序号分别为s1,s2----
 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;
}
//----从叶子到根逆向求每个字符的赫夫曼编码----
HC=(HuffmanCode)malloc((n+1)*sizeof(char*));
cd=(char*)malloc(n*sizeof(char));          
cd[n-1]='\0';                               //编码结束符
for(i=1;i<=n;++i)                           
{
 start=n-1;                              //编码结束符位置
 for(c=i,f=HT[i].parent;f!=0;c=f,f=HT[f].parent)
  if(HT[f].lchild==c)
cd[--start]='0';
  else
cd[--start]='1';
 HC[i]=(char*)malloc((n-start)*sizeof(char));
 strcpy(HC[i],&cd[start]);              
}
free(cd);
}

void main()

{
int *weigh;
int i,n;
HuffmanTree HT;

    HuffmanCode HC;
printf("............赫夫曼编码...........\n\n");
printf("请输入结点个数：");
scanf("%d",&n);
weigh=(int *)malloc(n*sizeof(int));

    printf("请输入%d个权值：",n);
for(i=0;i<n;i++)
{
scanf("%d",weigh+i);
}
HuffmanCoding(HT,HC,weigh,n);
for(i=1;i<=2*n-1;i++)
{
printf("%3d  %3d  %3d  %3d\n",HT[i].weight,HT[i].parent,HT[i].lchild,HT[i].rchild);
}
for(i=1;i<=n;i++)
{
printf("序号%2d:",i);
   printf("权值%3d:",HT[i].weight);
   printf("编码%s\n",HC[i]);
}

}