#define INT_MAX 10000 
#define ENCODING_LENGTH 1000 
#include "stdio.h" 
#include "string.h" 
#include "malloc.h" 
typedef enum{none,left_child,right_child} Which;//標(biāo)記是左孩子還是右孩子 
typedef char Elemtype; 
typedef struct TNode{ 
Elemtype letter; 
int weight; 
int parent; 
Which sigh; 
char *code; 
}HTNode,*HuffmanTree; 
int n; 
char coding[50];//儲(chǔ)存代碼 
char str[ENCODING_LENGTH];//保存要翻譯的句子 
void InitTreeNode(HuffmanTree &HT){//初始前N個(gè)結(jié)點(diǎn),后M-N個(gè)結(jié)點(diǎn)置空 
int i;int w;char c; 
int m=2*n-1; 
HuffmanTree p; 
HT=(HuffmanTree)malloc((m)*sizeof(HTNode)); 
printf("input %d database letter and weight",n); 
p=HT; 
getchar(); 
for (i=1;i<=n;i++){ 
scanf("%c%d",&c,&w); 
p->code='\0'; 
p->letter=c; 
p->parent=0; 
p->sigh=none; 
p->weight=w; 
p++; 
getchar(); 
} 
for (;i<=m;i++,p++){ 
p->code='\0'; 
p->letter=' '; 
p->parent=0; 
p->sigh=none; 
p->weight=0; 
} 
}//INITTREENODE 
void Select(HuffmanTree HT,int end,int *s1,int *s2){//在0~END之間,找出最小和次小的兩個(gè)結(jié)點(diǎn)序號(hào),返回S1,S2 
int i; 
int min1=INT_MAX; 
int min2; 
for (i=0;i<=end;i++){//找最小的結(jié)點(diǎn)序號(hào) 
if (HT[i].parent==0&&HT[i].weight<min1){ 
*s1=i; 
min1=HT[i].weight; 
} 
} 
min2=INT_MAX; 
for(i=0;i<=end;i++){//找次小結(jié)點(diǎn)的序號(hào) 
if (HT[i].parent==0&&(*s1!=i)&&min2>HT[i].weight){ 
*s2=i; 
min2=HT[i].weight; 
} 
} 
} 
void HuffmanTreeCreat(HuffmanTree &HT){//建立HUFFMAN樹 
int i;int m=2*n-1; 
int s1,s2; 
for(i=n;i<m;i++){ 
Select(HT,i-1,&s1,&s2); 
HT[s1].parent=i; 
HT[s2].parent=i; 
HT[s1].sigh=left_child; 
HT[s2].sigh=right_child; 
HT[i].weight=HT[s1].weight+HT[s2].weight; 
} 
} 

void HuffmanTreeCode(HuffmanTree HT){//HUFFMAN譯碼 
int i; 
char *temp; 
temp=(char *)malloc(n*sizeof(char)); 
temp[n-1]='\0'; 
int p;int s; 
for (i=0;i<n;i++){ 
p=i; 
s=n-1; 
while (HT[p].parent!=0){//從結(jié)點(diǎn)回溯,左孩子為0,右孩子為1 
if (HT[p].sigh==left_child) 
temp[--s]='0'; 
else if (HT[p].sigh==right_child) 
temp[--s]='1'; 
p=HT[p].parent; 
} 
HT[i].code=(char *)malloc((n-s)*sizeof(char));//分配結(jié)點(diǎn)碼長度的內(nèi)存空間 
strcpy(HT[i].code,temp+s); 
printf("%s\n",HT[i].code); 
} 
} 
void GetCodingSen(char *sencence){//輸入要編碼的句子 
int l; 
gets(sencence); 
l=strlen(sencence); 
sencence[l]='\0'; 
} 
void HuffmanTreeEncoding(char sen[],HuffmanTree HT){//將句子進(jìn)行編碼 
int i=0;int j; 
while(sen[i]!='\0'){ 
for(j=0;j<n;j++){ 
if (HT[j].letter==sen[i]) //字母吻合則用代碼取代 
{strcat(coding,HT[j].code); 
break; 
} 
} 
i++; 
if (sen[i]==32) i++; 
} 
printf("\n%s",coding); 
} 
void HuffmanTreeDecoding(HuffmanTree HT,char code[]){//HUFFMAN譯碼過程,將代碼翻譯為句子 
char sen[100]; 
char temp[50]; 
char voidstr[]=" "; 
int i;int j; 
int t=0;int s=0; 
for(i=0;i<strlen(code);i++){ 
temp[t++]=code[i]; 
for(j=0;j<n;j++){ 
if (strcmp(HT[j].code,temp)==0){//代碼段吻合 
sen[s]=HT[j].letter;s++; 
strcpy(temp,voidstr);//將TEMP置空 
t=0; 
break; 
} 
} 
} 
printf("\n%s",sen); 
} 

void main(){ 
HTNode hnode; 
HuffmanTree huff; 
huff=&hnode; 
printf("input the letter for coding number\n"); 
scanf("%d",&n); 
InitTreeNode(huff); 
HuffmanTreeCreat(huff); 
HuffmanTreeCode(huff); 
GetCodingSen(str); 
HuffmanTreeEncoding(str,huff); 
HuffmanTreeDecoding(huff,coding); 
}