C---求赫夫曼编码

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#include

#include

#include

typedef struct

      int weight;

      int parent, lchild, rchild;

}HTNode, *HuffmanTree;

typedef char **HuffmanCode;

void Huffmancoding(HuffmanTree &HT, HuffmanCode &HC, int w[], int n);

void Select(HuffmanTree &HT, int n,   int &a,   int &b);

//求赫夫曼编码

void Huffmancoding(HuffmanTree &HT, HuffmanCode &HC, int w[], int n)

      int m, i, start, f, c;

      int s1, s2;

    char *cd;

    s1=s2=m=i=start=f=c=0;

    //w存放n个字符的权值，构造赫夫曼树，并求出n个字符的赫夫曼编码，存放到HC

    if(n<=1)

        return;

    m=2*n-1;

    HT = (HuffmanTree)malloc((m)*sizeof(HTNode));

    for(i=0; i      {
          HT[i].weight = w[i];
          HT[i].lchild = 0;
          HT[i].rchild = 0; 
          HT[i].parent = 0;
      }
      for(i=n; i      {
          HT[i].weight = 0;
          HT[i].lchild = 0;
          HT[i].rchild = 0; 
          HT[i].parent = 0;
      }
      //建赫夫曼树
      for(i=n; i      {
          //在HT[1..i-1]选择parent为且weight最小的两个结点，其序号s1和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;
   
          printf("%d-%d-%d-%d/n", HT[s1].weight, HT[s1].parent, HT[s1].lchild, HT[s1].rchild);
          printf("%d-%d-%d-%d/n", HT[s2].weight, HT[s2].parent, HT[s2].lchild, HT[s2].rchild);
      }
   
      //从叶子到根逆向求每个节点的赫夫曼编码
      HC = (HuffmanCode)malloc((n)*sizeof(char *));
      cd = (char *)malloc(n*sizeof(char));
      cd[n-1]='/0';
      for(i=0; i      {
          start = n-1;
          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 Select(HuffmanTree &HT, int n,   int &a,   int &b)
  {
      int i;
        int temp;
   
      for(i=0; i<=n; i++)
          if(HT[i].parent == 0)
              a = i;
   
      for(i=0; i<=n; i++)
          if(HT[i].parent==0 && HT[i].weight              a=i;
   
      for(i=0; i<=n; i++)
          if(HT[i].parent==0 && i!=a)
              b=i;
   
      for(i=0; i<=n; i++)
          if(HT[i].parent==0 && i!=a && HT[i].weight              b=i;
   
  }
   
  int main()
  {
      int i;
      int w[8] = {23, 11, 5, 3, 29, 14, 7, 8};
   
      int n = 8;
   
      HuffmanTree ht;
      HuffmanCode hc;
   
      Huffmancoding(ht, hc, w, n);
   
      for(i=0; i          printf("%s/n", hc[i]);
      return 0;
  }

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