#include <iostream>
#include <cstring>

using namespace std;

int getMaxLen2(string str)
{    
    int len = str.length();
    int appear[256]={0};
    memset(appear,-1,sizeof(appear));
    int preCnt=1;
    appear[str[0]]=0;
    int ret = 1;    
    for(int i=1;i<len;++i)
    {
        int dif = i-appear[str[i]];
        if(dif>preCnt)
        {
            ++preCnt;
            if(preCnt>ret)
            {
                ret = preCnt;
            }
        }
        else
        {
            preCnt = dif;
        }
        appear[str[i]] = i;
    }
    return ret;
}

int getMaxLen(const string &s)  //有问题，如果输入为abcbgef

{

    int beg = ;

    int span = ;

    int maxspan = ;

    int hashTable[];

    for (int i = ; i < ; ++i)

        hashTable[i] = ;

    int lens = s.size();

    for(int i = ; i < lens; ++i)

    {

        int index = s[i];

        if (hashTable[index] == )

        {

            span = i - beg;

            if (span > maxspan)

                maxspan = span;

            beg++;

        }

        else

        {

            hashTable[s[i]] = ;

        }

    }

    return maxspan;

}

int main()

{

    const string a = "abmadsefadd";

    const string a1 = "abcbge";

    cout << getMaxLen(a) << endl;

    cout << getMaxLen(a1) << endl;   //错：输出为3

　　cout << getMaxLen2(a1) << endl;   //正确：输出为4

}