数据结构复习之利用Huffman树进行编码和译码

//编码#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<queue>
#include<fstream>
#include<map>
using namespace std;

typedef struct HuffmanNode{
    int w;//节点的权值
    int ld, rd;//左右孩子节点
    int p;//父节点
    char ch;//当前节点的字符
    HuffmanNode(){
        ld = rd = p = -1;
    }
}huffmanNode, *pHuffmanNode;

typedef pair<int, int> pii;//haffuman节点和它的编号 

bool operator > (pii x, pii y){
    return x.first > y.first;
}

struct Huffman{
    int cntNode;//总结点的个数
    string orgCode;
    string huffmanCode;
    pHuffmanNode huffman =    NULL;
    priority_queue<pii, vector<pii>, greater<pii> >qNode;
    map<string, char> huffmanMapx;//哈夫曼编码对应字符
    map<char, string> huffmanMapy;//字符对应哈夫曼编码
    void initHuffman(char *str){
        orgCode = str;
        cntNode = 0;
        int cnt[150];//统计每一个节点的个数
        memset(cnt, 0, sizeof(cnt));
        for(int i=0; str[i]; ++i){
            if(cnt[str[i]]==0) ++cntNode;
            ++cnt[str[i]];
        }
        huffman = new HuffmanNode[2*(cntNode)];
        int index = 0;
        for(int i=0; i<150; ++i){
            if(cnt[i]!=0){
                huffman[index].w = cnt[i];
                huffman[index].ch = i;
                qNode.push(make_pair(huffman[index].w, index));
                ++index;
            }
        }
        while(qNode.size()>=2) {
            pii ldPii = qNode.top();
            qNode.pop();
            pii rdPii = qNode.top();
            qNode.pop();
            huffman[index].w = ldPii.first + rdPii.first;
            huffman[index].ld = ldPii.second;
            huffman[index].rd = rdPii.second;
            huffman[ldPii.second].p = index;
            huffman[rdPii.second].p = index;
            qNode.push(make_pair(huffman[index].w, index));
            ++index;
        }
    }

    void huffmanCoding() {
        for(int i=0; i<cntNode; ++i){//从每一个孩子节点向上寻找
            string code = "";
            for(int child=i, p=huffman[child].p; ~p; child = p, p = huffman[child].p) {
                if(huffman[p].ld == child){//左子树
                    code += ‘0‘;
                } else if(huffman[p].rd == child){//右子树
                     code += ‘1‘;
                }
            }
            reverse(code.begin(), code.end());
            huffmanMapx.insert(make_pair(code, huffman[i].ch));
            huffmanMapy.insert(make_pair(huffman[i].ch, code));
        }
    }

    void outHuffmanTree(fstream &fout, int f){
        if(huffman[f].ld==-1 && huffman[f].rd==-1){
            fout<<0<<" ";
            return ;
        } else {
            fout<<1<<" ";
            outHuffmanTree(fout, huffman[f].ld);
            outHuffmanTree(fout, huffman[f].rd);
        }
    }

    void outHuffmanCode(){
        huffmanCode = "";//存储字符串的哈夫曼编码之后的内容
        fstream fout("out.txt", ios_base::out);
        for(int i=0; i<orgCode.length(); ++i){
            huffmanCode += huffmanMapy[orgCode[i]];
        }
        cout<<huffmanCode<<endl;
        fout<<huffmanCode<<endl;//想文件中输入huffman编码
        int f = 2*cntNode-2;//huffman树的父节点
        outHuffmanTree(fout, f);
        fout<<endl;
        for(map<string, char>::iterator it = huffmanMapx.begin(); it!=huffmanMapx.end(); ++it){
            cout<<it->first << " -> " << it->second<<endl;
            fout<<it->first<<" "<<it->second<<endl; //向文件中输入HuffmanMap
        }
    }
};

int main(){
    char str[100];
    Huffman huffman;
    gets(str);
    huffman.initHuffman(str);
    huffman.huffmanCoding();
    huffman.outHuffmanCode();
    return 0;
}

//译码#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<queue>
#include<fstream>
#include<map>
using namespace std;

typedef struct HuffmanTreeNode{
    HuffmanTreeNode *ld, *rd;
    HuffmanTreeNode(){
        ld = NULL;
        rd = NULL;
    }
} *pHuffmanTreeNode;

struct Huffman{
    pHuffmanTreeNode T;
    string code;
    map<string, char>huffmanMapx;

    void buildT(fstream &fin, pHuffmanTreeNode &T){
        int w;
        fin>>w;
        T = new HuffmanTreeNode();
        if(w==0)
            return ;
         buildT(fin, T->ld);
         buildT(fin, T->rd);
    }

    void outT(pHuffmanTreeNode T){
        if(T->ld != NULL){
            cout<<0<<endl;
            outT(T->ld);
        }
        else return;
        if(T->rd != NULL){
            cout<<1<<endl;
            outT(T->rd);
        }
    }

    void initHuffmanTree(){
        fstream fin("in.txt", ios_base::in);
        T = NULL;
        fin>>code;
        buildT(fin, T);
        //outT(T);
        string mapContent;
        while(getline(fin, mapContent)){
            int index = mapContent.find_first_of(‘ ‘);
            huffmanMapx.insert(make_pair(mapContent.substr(0, index), mapContent[index+1]));
        }
    }

    void outHuffmanEncode(){
        string encode = "", cd="";
        initHuffmanTree();
        pHuffmanTreeNode p = T;
        for(int i=0; i<code.length(); ++i){
            if(p->ld==NULL && p->rd==NULL){
                encode+=huffmanMapx[cd];
                cd="";
                --i;
                p=T;
            } else {
                cd+=code[i];
                if(code[i]==‘0‘)
                    p=p->ld;
                else if(code[i]==‘1‘)
                    p=p->rd;
            }
            if(i==code.length()-1) encode+=huffmanMapx[cd];
        }
        cout<<encode<<endl;
    }
};

int main(){
    Huffman huffman;
    huffman.outHuffmanEncode();
    return 0;
}

操作流程：

文本内容：aaaaaaabbbbbccdddd, and I am a student, my name is hjzgg!

1.首先利用‘‘编码"工具将文本编码，会输出一个out.txt的文本，将out.txt文本中的内容发送给你的好友。

2.接受到out.txt文本的内容后，将内容复制到文本名为in.txt的文件中，利用"译码"工具（保证in.txt和译码工具在同一目录下）可以查看文本内容。

3.其中out.txt文本的格式如下：