哈夫曼树（c语言实现）

红太狼 2022-03-26 01:50 276阅读 0赞

待压缩的读入文件：Compress\_read.txt

压缩后的写入文件：Compress\_write.txt

解压缩的写入文件：Decompress\_write.txt

以上文件请自行创建，其中待压缩文本放在Compress\_read.txt中即可编译运行。

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <limits.h>
    typedef struct //单个符号的结构体
    {
        char c;  //字符
        unsigned int count;  //出现次数
        unsigned char huffcode[300]  //编码
    }struct_symbol;
    
    typedef struct  //文件字符的结构体
    {
       struct_symbol symbol_array[128];  //各种字符
       unsigned char number;  //字符种类个数
    }struct_file;
    
    typedef struct node //哈夫曼树静态三叉链表
    {
        struct_symbol symbol;
        int lchild;
        int rchild;
        int parent;
    }HTNODE;
    
    struct_file symbol_file;
    
    void InitHT(HTNODE *HT)  //初始化
    {
        for(int i=0;i<(2*symbol_file.number-1);i++)
        {
            HT[i].lchild=-1;
            HT[i].rchild=-1;
            HT[i].parent=-1;
        }
    }
    
    void Input(HTNODE *HT)  //输入叶节点权值
    {
        for(int i=0;i<symbol_file.number;i++)
        {
            HT[i].symbol.c = symbol_file.symbol_array[i].c;
            HT[i].symbol.count = symbol_file.symbol_array[i].count;
        }
    }
    
    void SelectMin(HTNODE *HT,int n,int *p1,int *p2)  //求两个最小权值
    {
        int i,j;
        for(i=0;i<=n;i++)
            if(HT[i].parent==-1)
        {
            *p1 = i;
            break;
        }
        for(j=i+1;j<=n;j++)
            if(HT[j].parent==-1)
        {
            *p2 = j;
            break;
        }
        for(i=0;i<=n;i++)
            if((HT[*p1].symbol.count>HT[i].symbol.count)&&(HT[i].parent=-1)&&(*p2!=i))
            *p1=i;
        for(j=0;j<=n;j++)
            if((HT[*p2].symbol.count>HT[j].symbol.count)&&(HT[j].parent=-1)&&(*p1!=j))
            *p2=j;
    }
    
    void ReadCompress()   //读入待压缩文件
    {
        FILE *fp;
        char ch;
        int flag,i,counter=0;
        fp=fopen("Compress_read.txt","rb");
        if(fp==NULL)
        {
            printf("Compress_read.txt can not be read!\n");
            exit(0);
        }
        printf("成功读入待压缩文件！\n\n");
        symbol_file.number = 0;
        while(1)    //读入文件，统计各字符次数
        {
            fscanf(fp,"%c",&ch);
            counter++;
            flag = 0;
            if(ch=='#')
                break;
            /*if(ch=='\r')
                continue;*/
            for(i=0;i<symbol_file.number;i++)
            {
                if(ch ==symbol_file.symbol_array[i].c)
                {
                    symbol_file.symbol_array[i].count++;
                    flag = 1;
                    break;
                }
            }
            if(!flag)
            {
                symbol_file.symbol_array[symbol_file.number].c = ch;
                symbol_file.symbol_array[symbol_file.number].count = 1;
                symbol_file.number++;
            }
        }
        fclose(fp);
        for(int i=0;i<symbol_file.number;i++)
            printf("字符%c    出现次数%d\n",symbol_file.symbol_array[i].c\
                   ,symbol_file.symbol_array[i].count);
        printf("\n待压缩文件总字节数为：%d\n",counter);
    }
    
    void CreatHT(HTNODE *HT)
    {
        int i,p1,p2;
        InitHT(HT);
        Input(HT);
        for(i=symbol_file.number;i<(2*symbol_file.number-1);i++)
        {
            SelectMin(HT,i-1,&p1,&p2);
            HT[p1].parent = HT[p2].parent = i;
            HT[i].lchild = p1;
            HT[i].rchild = p2;
            HT[i].symbol.count = HT[p1].symbol.count + HT[p2].symbol.count;
            HT[p1].symbol.count = INT_MAX;  //即标记该处访问过了
            HT[p2].symbol.count = INT_MAX;
        }
    }
    
    void HuffmanEncoding(HTNODE *HT)  //编码并存到symbol.huffcode中
    {
        int c,p,i,j;
        int start;
        for(i=0;i<symbol_file.number;i++)  //初始化
            for(j=0;j<300;j++)
        {
            HT[i].symbol.huffcode[j] ='\0';
        }
        for(i=0;i<symbol_file.number;i++)
        {
            c = i;
            start = symbol_file.number;
            while((p=HT[c].parent)>=0)
            {
                HT[i].symbol.huffcode[--start] = (HT[p].lchild==c)?'0':'1';
                c = p;  //继续上溯
            }
        }
    }
    
    void WriteCompress(HTNODE *HT)  //压缩并写入文件
    {
        FILE *fp_read,*fp_write;
        unsigned char ch,buffer=0;
        int i,j,index=7,counter=0;
        fp_read=fopen("Compress_read.txt","rb");
        fp_write=fopen("Compress_write.txt","wb");
        if(fp_read==NULL)
        {
            printf("读入文件Compress_read.txt失败！\n");
            return -1;
        }
        if(fp_write==NULL)
        {
            printf("写入文件Compress_write.txt失败！\n");
            return -1;
        }
        while(1)
        {
            fscanf(fp_read,"%c",&ch);
            if(ch=='#')
            {
                fprintf(fp_write,"%c",buffer);
                counter++;
                break;
            }
            /*if(ch=='\r')
                continue;*/
            for(i=0;i<symbol_file.number;i++)
            {
                if(HT[i].symbol.c==ch)
                {
                    for(j=0;j<300;j++)
                        if(HT[i].symbol.huffcode[j]!='\0')
                        {
                            buffer |=(HT[i].symbol.huffcode[j]-'0')<<index;
                            index--;
                            if(index==-1)
                            {
                                fprintf(fp_write,"%c",buffer);
                                buffer = 0;
                                index = 7;
                                counter++;
                            }
                        }
                }
            }
        }
        printf("文件已成功压缩！\n\n");
        printf("压缩文件总字节数为%d\n",counter);
        fclose(fp_write);
        fclose(fp_read);
    }
    
    void Decompress(HTNODE *HT)  //解压文件
    {
        unsigned char ch;
        FILE *fp_read,*fp_write;
        int i,j,index,count,child,parent;
        printf("\n解压产生字符总数：%d\n",HT[(2*symbol_file.number-2)].symbol.count);
        fp_read=fopen("Compress_write.txt","rb");
        fp_write=fopen("Decompress_write.txt","wb");
        if(fp_read==NULL)
        {
            printf("读入文件Compress_write.txt失败！\n");
            return -1;
        }
        if(fp_write==NULL)
        {
            printf("写入文件Decompress_write.txt失败！\n");
            return -1;
        }
        index = 7;  //初始偏移量
        parent =2*symbol_file.number-2;  //根的位置
        count = HT[parent].symbol.count;  //字符总数
        while(1)
        {
            fscanf(fp_read,"%c",&ch);
            index = 7;
            while(index!=-1)
            {
                if(((ch>>index)&1)==0)
                    child = HT[parent].lchild;
                else
                    child = HT[parent].rchild;
                if(HT[child].lchild<0&&HT[child].rchild<0)  //叶节点
                {
                    fprintf(fp_write,"%c",HT[child].symbol.c);
                    parent =2*symbol_file.number-2;
                    count --;
                }
                else
                    parent = child;
                index--;
                if(count ==0)
                {
                    printf("文件已成功解压！\n");
                    fclose(fp_write);
                    fclose(fp_read);
                    return;
                }
            }
        }
    }
    
    int main()
    {
        HTNODE *HT;
        ReadCompress();
        HT=(HTNODE*)malloc((2*symbol_file.number-1)*sizeof(HTNODE));
        CreatHT(HT);
        HuffmanEncoding(HT);
        WriteCompress(HT);  //压缩
        Decompress(HT); //文件解压缩
        return 0;
    }