LZW压缩算法

#include<iostream>using namespace std;#include<string>//LZW压缩和解压缩typedef struct Dict{       string _s;       int _code;}Dict;class ComPRess{public:       Compress(int maxSize,string text)       {              _maxSize = maxSize;              _code = new int[maxSize];              _size = 0;              _text = text;              _dict = new Dict[_maxSize];              _dictSize = 0;              //过滤0号位置              Insert("#");              //向字典中插入26个字母              string s = "A";              for (int i = 0; i < 26; ++i)              {                     Insert(s);                     s[0]++;              }       }       ~Compress()       {              delete[] _code;              delete[] _dict;              _code = NULL;              _dict = NULL;              _maxSize = 0;              _size = 0;       }       string Encode()       {              string s;//存储压缩后的字符串              string cur;              char next;              int i = 0;              while (i < _text.size())              {                     cur.insert(cur.size(),1, _text[i]);                     i++;                     next = _text[i];                     while (FindCode(cur) != -1)//当前串在字典中                     {                                 cur.insert(cur.size(), 1, next);                           ++i;                           if (i != _text.size())                                  next = _text[i];                           else                                  break;                     }                     if (i != _text.size())                     {                           char c = cur.at(cur.size() - 1);                           cur.erase(cur.end()-1);                           _code[_size] = FindCode(cur);                           ++_size;                           cur += c;                           c =  _code[_size-1];                           s.push_back(c);                           Insert(cur);                     }                                  if(i == _text.size() && FindCode(cur) != -1)                     {                           _code[_size] = FindCode(cur);                           s.push_back(_code[_size]);                           break;                     }                                  --i;                     cur.clear();              }              return s;       }       string Decode(const string& s)       {              string text;              string cur;              if (s.size() <= 0)                     return s;              int code;              for (int i = 0; i < s.size(); ++i)              {                     code = (int)(s[i]);                     cur = FindSeq(code);                     text += cur;              }              return text;       }       void PrintDict()       {              cout<<"seq  code"<<endl;              for (int i = 0; i < _dictSize; ++i)              {                     cout << _dict[i]._s << "     " << _dict[i]._code<<endl;              }       }protected:       int FindCode(const string& s)       {              for (int i = 0; i < _dictSize; ++i)              {                     if (s == _dict[i]._s)                           return i;              }              return -1;       }       string FindSeq(int code)       {              return _dict[code]._s;       }       void Insert(string seq)       {              _dict[_dictSize]._s = seq;              _dict[_dictSize]._code = _dictSize;              _dictSize++;       }private:       Dict* _dict;       int _dictSize;       int* _code;       int _size;       int _maxSize;       string _text;};int main(){       string text;       cin >> text;       Compress c(100,text);       //c.PrintDict();       string s = c.Encode();     //  c.PrintDict();       //cout << s;       cout<<c.Decode(s)<<endl;       system("pause");       return 0;}代码运行结果：当然了，要实现真正的压缩，就要把压缩信息写进文件。如果要将压缩和解压缩进行分离的话，还需要在解压缩的时候，完成一次字典的填充工作。这里只是为了说明算法而已。