#include <iostream>
#include <stdio.h>
using namespace std;

string RunLengthEncoding(string str){
    int size = str.size();
    if(size <= 0){
        return "";
    }//if
    string result(str.substr(0,1));
    int count = 0;
    char * temp = new char[100];
    for(int i = 0;i < size;++i){
        if(i > 0 && str[i] != str[i-1]){
            if(count > 1){
               sprintf(temp,"%d",count);
               result += temp;
            }//if
            result += str[i];
            count = 0;
        }//if
        ++count;
    }//for
    if(count > 1){
        sprintf(temp,"%d",count);
               result += temp;
    }//if
    return result;
}

string RunLengthDecoding(string str)
{
    string result;
    char temp = str[0];
    for (int i = 0; i < str.size();)
    {
        if(str[i] < '0' || str[i] > '9')
        {
            if(str[i+1]< '0' || str[i+1] > '9')
            {
                result += str[i];
                i++;

            }
            else
            {
                int number = 0;
                temp = str[i];
                i++;
                while( str[i] >= '0' && str[i] <= '9')
                {
                    number *= 10;
                    number += (str[i] - '0');
                    i++;
                }
                while(number--)
                {
                    result += temp;
                }
            }
        }
    }
    return result;
}
int main(){
    //string str("aaaaaaaaaabbbaxxxxyyzyx");
    //string str("abbbb");
    string str("a");
    string result = RunLengthEncoding(str);
    string str2("aaaaaaaaaabbbaxxxxyyzyx");
    string result2 = RunLengthEncoding(str2);
    cout<<"压缩后数据->"<<result<<endl;
    cout<<"压缩后数据->"<<result2<<endl;

    string decoding = RunLengthDecoding(result2);
    cout<<"解压缩后数据->"<<decoding<<endl;    
    return 0;
}

附件是huffman编码的实例，主要要弄明白精华。