• 哈夫曼树

    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. }