哈夫曼树

  1. #include <stdio.h>
  2. #define N 50        /*叶子结点数*/
  3. #define M 2*N-1        /*树中结点总数*/
  5. typedef struct
  6. {
  7.     char data;        /*结点值*/
  8.     double weight;    /*权重*/
  9.     int parent;        /*双亲结点*/
  10.     int lchild;        /*左孩子结点*/
  11.     int rchild;        /*右孩子结点*/
  12. } HTNode;
  14. typedef struct
  15. {
  16.     char cd[N];        /*存放哈夫曼码*/
  17.     int start;
  18. } HCode;
  20. void CreateHT(HTNode ht[],int n)
  21. {
  22.     int i,k,lnode,rnode;
  23.     double min1,min2;
  24.     for (i=0;i<2*n-1;i++)            /*所有结点的相关域置初值-1*/
  25.         ht[i].parent=ht[i].lchild=ht[i].rchild=-1;
  26.     for (i=n;i<2*n-1;i++)            /*构造哈夫曼树*/
  27.     {
  28.         min1=min2=32767;            /*lnode和rnode为最小权重的两个结点位置*/
  29.         lnode=rnode=-1;
  30.         for (k=0;k<=i-1;k++)
  31.             if (ht[k].parent==-1)    /*只在尚未构造二叉树的结点中查找*/
  32.             {
  33.                 if (ht[k].weight<min1)
  34.                 {
  35.                     min2=min1;rnode=lnode;
  36.                     min1=ht[k].weight;lnode=k;
  37.                 }
  38.                 else if (ht[k].weight<min2)
  39.                 {
  40.                     min2=ht[k].weight;rnode=k;
  41.                 }
  42.             }
  43.         ht[i].weight=ht[lnode].weight+ht[rnode].weight;
  44.         ht[i].lchild=lnode;ht[i].rchild=rnode;
  45.         ht[lnode].parent=i;
  46.         ht[rnode].parent=i;
  47.     }
  48. }
  50. void CreateHCode(HTNode ht[],HCode hcd[],int n)
  51. {
  52.     int i,f,c;
  53.     HCode hc;
  54.     for (i=0;i<n;i++)    /*根据哈夫曼树求哈夫曼编码*/
  55.     {
  56.         hc.start=n;c=i;
  57.         f=ht[i].parent;
  58.         while (f!=-1)    /*循序直到树根结点*/
  59.         {
  60.             if (ht[f].lchild==c)    /*处理左孩子结点*/
  61.                 hc.cd[hc.start--]='0';
  62.             else                    /*处理右孩子结点*/
  63.                 hc.cd[hc.start--]='1';
  64.             c=f;f=ht[f].parent;
  65.         }
  66.         hc.start++;        /*start指向哈夫曼编码最开始字符*/
  67.         hcd[i]=hc;
  68.     }
  69. }
  71. void DispHCode(HTNode ht[],HCode hcd[],int n)
  72. {
  73.     int i,k;
  74.     double sum=0,m=0;
  75.     int j;
  76.     printf("输出哈夫曼编码:\n"); /*输出哈夫曼编码*/
  77.     for (i=0;i<n;i++)
  78.     {
  79.         j=0;
  80.         printf("   %c:",ht[i].data);
  81.         for (k=hcd[i].start;k<=n;k++)
  82.         {
  83.             printf("%c",hcd[i].cd[k]);
  84.             j++;
  85.         }
  86.         m+=ht[i].weight;
  87.         sum+=ht[i].weight*j;
  88.         printf("\n");
  89.     }
  90. }
  92. void main()
  93. {
  94.     int n=5,i;        /*n表示初始字符串的个数*/
  95.     char str[]={'a','b','c','d','e'};
  96.     double fnum[]={4,2,1,7,3};
  97.     HTNode ht[M];
  98.     HCode hcd[N];
  99.     for (i=0;i<n;i++)
  100.     {
  101.         ht[i].data=str[i];
  102.         ht[i].weight=fnum[i];
  103.     }
  104.     printf("\n");
  105.     CreateHT(ht,n);
  106.     CreateHCode(ht,hcd,n);
  107.     DispHCode(ht,hcd,n);
  108.     printf("\n");
  109. }