赫夫曼树

什么是赫夫曼树?

　　赫夫曼树:树的带权路径长度WPL最小的二叉树，又称最优二叉树。

void HuffmanCoding(HuffmanTree *HT,HuffmanCode *HC,int *w,int n)
{
    int i=0,s1=0,s2=0,c=0,start=0,f=0;
    if(n <=1 ) return;
    int m=2*n-1;
    char *cd;
    HuffmanTree p;
    *HT=(HuffmanTree)malloc((m+1)*sizeof(HTNode));
    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){
        Select(HT,i-1,&s1,&s2);  //选择parent为0，且weight最小的两个结点，序号分别为s1,s2
        printf("s1: %d, s2: %d\n",s1,s2);
        (*HT)[s1].parent=i;
        (*HT)[s2].parent=i;
        (*HT)[i].weight=(*HT)[s1].weight+(*HT)[s2].weight;
        (*HT)[i].lchild=s1;
        (*HT)[i].rchild=s2;
    }
    *HC=(HuffmanCode)malloc((n+1)*sizeof(char *));
    cd=(char *)malloc(n*sizeof(char));
    cd[n-1]='\0';
    for(i=1;i<=n;++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);
}