typedef struct{unsigned int weight;unsigned int parent,lchild,rchild;
}HTNode,*HuffmanTree;//动态分配数组存储哈夫曼树
typedef char **HuffmanCode;//动态分配数组存储哈夫曼编码表

#include<iostream.h>
//using namespace std;
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<fstream.h>
#define num 1000
typedef struct//哈夫曼树的结构体
{char ch;int weight;//权值int parent,lchild,rchild;
}HTNode,*HuffmanTree;
typedef char **HuffmanCode;
void Select(HuffmanTree &HT,int a,int *p1,int *p2)
//Select函数，选出HT树到a为止，权值最小且parent为0的2个节点
{int i,j,x,y,count,temp;for(j=1,count=1;j<=a;j++){if(HT[j].parent==0){if(count==1)x=j;if(count==2)y=j;count++;            }if(count>2)break;}if(HT[x].weight>HT[y].weight)//令x结点权值小于y结点权值
    {temp=y;y=x;x=temp;}i=(x>y?x:y)+1;while(i<=a){if(HT[i].parent==0){if(HT[i].weight<HT[x].weight){y=x;x=i;}else{if(HT[i].weight>=HT[x].weight&&HT[i].weight<HT[y].weight)y=i;}}i++;}*p1=HT[x].weight<=HT[y].weight?x:y;*p2=HT[x].weight>HT[y].weight?x:y;}
void HuffmanCoding(HuffmanTree &HT,HuffmanCode &HC,int n)//构建赫夫曼树HT，并求出n个字符的赫夫曼编码HC
{int i,start,c,f,m,w;int p1,p2;char *cd,z;if(n<=1)exit(1);m=2*n-1;//n个叶子结点的哈夫曼树共有2n-1个结点HT=(HuffmanTree)malloc((m+1)*sizeof(HTNode));//0号单元未使用for(i=1;i<=n;i++)//初始化n个叶子结点
    {printf("请输入第%d字符信息和权值：",i);scanf("%c%d",&z,&w);while(getchar()!='\n'){continue;}HT[i].ch=z;HT[i].weight=w;HT[i].parent=0;HT[i].lchild=0;HT[i].rchild=0;}for(i=n+1;i<=m;i++)//初始化其余结点
    {HT[i].ch='0';HT[i].weight=0;HT[i].parent=0;HT[i].lchild=0;HT[i].rchild=0;}for(i=n+1;i<=m;i++)//建立哈夫曼树
    {Select(HT,i-1,&p1,&p2);HT[p1].parent=i;HT[p2].parent=i;HT[i].lchild=p1;HT[i].rchild=p2;HT[i].weight=HT[p1].weight+HT[p2].weight;}//从叶子到根逆向求每个字符的哈夫曼编码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';elsecd[--start]='1';}HC[i]=(char *)malloc((n-start)*sizeof(char));strcpy(HC[i],&cd[start]);}free(cd);
}
int main()
{char code[100],h[100],hl[100];int n,i,j,k,l;ifstream input_file; ofstream output_file;FILE *fp1,*fp2,*fp3,*fp4,*fp5;char choice,str[100];HuffmanTree HT;HuffmanCode HC;cout<<"            哈夫曼编码器\n";while(choice!='Q'&&choice!='q')            //当choice的值不为q且不为Q时循环
    {cout<<"功能: "<<"I(初始化)"<<""<<"E(编码)"<<""<<"D(译码)"<<""<<"P(打印)"<<""<<"Q(退出)\n";cout<<"请输入您要选择的功能：";cin>>choice;if(choice=='I'||choice=='i')              //初始化赫夫曼树
        {cout<<"请输入字符个数：";cin>>n;HuffmanCoding(HT,HC,n);for(i=1;i<=n;++i){cout<<HT[i].ch<<":"<<HC[i]<<endl;}fp1=fopen("hfmTree.txt","w");for(i=1;i<=n;++i){fprintf(fp1,"(%c %s)\n",HT[i].ch,HC[i]);}fclose(fp1);cout<<"赫夫曼树已经创建完毕，并且已经放入hfmTree.txt文件中!"<<endl;}else if(choice=='E'||choice=='e')           //进行编码，并将字符放入ToBeTran.txt，码值放入CodeFile.txt中
        {printf("请输入字符：");gets(str);fp2=fopen("ToBeTran.txt","w");fprintf(fp2,"%s",str);fclose(fp2);fp3=fopen("CodeFile.txt","w");for(i=0;i<strlen(str);i++){for(j=1;j<=n;++j){if(HT[j].ch==str[i]){fprintf(fp3,"%s",HC[j]);break;}}}fclose(fp3);cout<<"\n";fp4=fopen("CodeFile.txt","r"); char H1;//从CodeFile.txt中读入编码，输出在终端cout<<"编码值为：\n";while(!feof(fp4)){H1=fgetc(fp4);cout<<H1;}fclose(fp4);cout<<"\n编码完毕，并且已经存入CodeFile.txt文件！\n";}else if(choice=='D'||choice=='d')     //读入CodeFile.txt中的编码进行译码，将译出来的字符放入Textfile.txt中
        {input_file.open("CodeFile.txt");if(!input_file){cout<<"can't open file!"<<endl;return 1;}input_file>>h;input_file.close();output_file.open("Textfile.txt");if(!output_file){cout<<"can't open file!"<<endl;return 1;}k=0;while(h[k]!='\0')           //先用编码中的前几个和字符的编码相比较，然后往后移
            {for(i=1;i<=n;i++){l=k;for(j=0;j<strlen(HC[i]);j++,l++){hl[j]=h[l];}hl[j]='\0';if(strcmp(HC[i],hl)==0){output_file<<HT[i].ch;k=k+strlen(HC[i]);break;}}}output_file.close();input_file.open("Textfile.txt");if(!input_file){cout<<"can't open file!"<<endl;return 1;}//    input_file>>h;input_file.getline(h,100);//获取文件里的一行cout<<"译码结果为：";printf("%s\n",h);input_file.close();cout<<"译码结果已存入Textfile.txt中\n";}else if(choice=='P'||choice=='p')//每行50个代码
        {char a[num];fp4=fopen("CodeFile.txt","r"); fgets(a,num,fp4);cout<<"打印代码文件:"<<endl;int l=strlen(a);for(int j=0;j<l;j++){cout<<a[j];if((j+1)%50==0)cout<<endl;}fclose(fp4);fp5=fopen("CodePrint.txt","w");for(int k=0;k<l;k++){fprintf(fp5,"%c",a[k]);if((k+1)%50==0){fprintf(fp5,"\n");}}cout<<"\n该字符形式已存入CodePrint.txt中\n";fclose(fp5);}else if(choice=='Q'||choice=='q')            //退出程序
        { exit(0);}else               //如果选了选项之外的就让用户重新选择
        {cout<<"您没有输入正确的步骤，请重新输入！"<<endl;}cout<<endl;}return 0;
}