void HuffmanCoding(HuffmanTree HT,HuffmanCode HC)
{
int c,p,i;
char cd[n];
int start;
cd[num]='\0';
for(i=1;i<=num;i++)
{
start=num;
c=i;
while((p=HT[c].parent)>0)
{
cd[--start]=(HT[p].left==c)?'0':'1';
c=p;
}
strcpy(HC[i].bits,&cd[start]) ;
HC[i].length=num-start;
}
}