赫夫曼树和赫夫曼编码

#include <stdio.h>

#define MAXSIZE 128
//字符表
typedef struct {
    char ch;
    unsigned int repeat;
}table;

//哈夫曼树节点
typedef struct {
    char data;
    unsigned int weight;
    int  parent,lchild, rchild;
}hfmtree;

//哈夫曼编码
typedef struct {
    char data;
    char code[128];
}hfmcode;

hfmtree Hdata[2*MAXSIZE-1];
hfmcode code[MAXSIZE];
int count = 0;

void insrtch(char str[],char ch){//字符串首端插入字符
    int len = 0;
    while(str[len]!='\0'){
        len++;
    }
    str[len+1] = '\0';
    while(len!=0){
        str[len] = str[len-1];
        len--;
    }
    str[0] = ch;
}

int length(char *str){//求字符串长度
    int len = 0;
    while(str[0]!='\0'){
        len ++;
        str++;
    }
    return len;
}

int Getext(){//读文本文件，获取字符重复次数，存入字符表
    FILE *fp;
    int i,p;
    char buf;
    count = 0;
    table tb[MAXSIZE]={0};
    fopen_s(&fp,"d:\\text.txt","r");
    while(fread(&buf,1,1,fp)){
        printf("%c",buf);
        p = (int)buf;
        tb[p].ch = buf;
        (tb[p].repeat) ++;
    }
    fclose(fp);
    //赫夫曼森林种树
    for(i=0;i<MAXSIZE;i++){
        if(tb[i].repeat !=0){
            Hdata[count].data=tb[i].ch;
            Hdata[count].weight=tb[i].repeat;
            count++;
        }
    }
    //打印字符表
    printf_s("\nNow,Output the Text Table......\n");
    getchar();
    for(i=0;i<count;i++){
        printf("%d,%c,%u\n",i,Hdata[i].data,Hdata[i].weight);
    }
    return 0;
}

int BuildTree(){//建立哈夫曼树
    int i, j, k = 0;
    int reset = 0;
    int tnum = 0;
    int p1 = count;
    unsigned int  small = 65636 ;
    for (i=0;i<2*count-2 ;i++){
        for (j = 0; j < p1; j++){
            if(Hdata[j].parent==-1) tnum++;
            if ((Hdata[j].weight < small )&& (Hdata[j].parent == -1)) {
                small = Hdata[j].weight ;
                k = j;
            }
        }
        if (reset == 0){
            Hdata[p1].weight += Hdata[k].weight ;
            Hdata[p1].lchild = k;
            Hdata[k].parent = p1;
            reset = 1;
        }
        else{
            Hdata[p1].weight += Hdata[k].weight ;
            Hdata[p1].rchild = k;
            Hdata[k].parent = p1;
            reset = 0; 
            p1++;
        }
        if (tnum<2) break;
        tnum=0;
        small = 65636;
    }
    printf_s("\nNow,Output the Huffman Tree......\n");
    getchar();
    for(i=0;i<2*count-1;i++)
        printf("%d: %c,%u,%d,%d,%d\n",i,Hdata[i].data,Hdata[i].weight,Hdata[i].parent , Hdata[i].lchild,Hdata[i].rchild );
    return 0;
}

int Code(){//生成前缀编码
    int i;
    printf_s("\nNow,Output the Huffman Code......\n");
    getchar();
    int  c, p;                          
    for (i = 0; i < count; i++){
        code[i].data =  Hdata[i].data ;
        code[i].code[0] =  '\0' ;
        c = i;
        p = Hdata[c].parent;
        while (p != -1){
            if (Hdata[p].lchild == c) insrtch(code[i].code,'0');
            else insrtch(code[i].code,'1');
            c = p;
            p = Hdata[c].parent;
        }
    }
    for (i = 0; i < count; i++){
        printf("%c: %s\n",code[i].data,code[i].code);
    }
    return 0;
}

int Encode(){//对文本文件编码
    FILE *fpr,*fpw;
    int i;
    char ch ,*str;
    fopen_s(&fpr,"d:\\text.txt","r");
    fopen_s(&fpw,"d:\\code.txt","w");
    while(fread(&ch,sizeof(char),1,fpr)){
        for (i=0;i<count;i++){
            if(code[i].data == ch){
                str =  code[i].code;
                fwrite(str,sizeof(char),length(str),fpw);
                break;
            }
        }
    }
    printf("\n");
    fclose(fpr);
    fclose(fpw);
    return 0;
}

int Decode(){//文本文件存储的二进制码解码
    FILE *fp;
    int i,m;
    char buf;
    printf_s("\nNow,We can decode a binary string read from a text file......\n");
    getchar();
    fopen_s(&fp,"d:\\code.txt","r");
    m = 2*count- 1;
    i = m -1;
    while(fread(&buf,1,1,fp)){
        if (buf == '0') i = Hdata[i].lchild;
        else i = Hdata[i].rchild;

        if (Hdata[i].lchild == -1){
            printf_s("%c",Hdata[i].data);
            i = m -1;
        }
    }
    fclose(fp);
    printf_s("\nCongratulations! We Success !\n");
    return 0;
}

int main(){
    for(int i = 0;i<2*MAXSIZE-1;i++){//初始化赫夫曼树
        Hdata[i].data='0';
        Hdata[i].weight=0;
        Hdata[i].parent=-1;
        Hdata[i].lchild=-1;
        Hdata[i].rchild=-1;
    }

    Getext();//获得字符重复次数
    BuildTree();//建立赫夫曼二叉树，数组存储
    Code();//前缀编码
    Encode();//对一串文字进行编码，保存到文本文件
    Decode();//对输入的一个或一串编码进行解码
    getchar();
    return 0;
}