字符串中最长的不重合字串长度

#include <iostream>
using namespace std;

int getMaxLen(const string &s)
{
    int beg = 0;
    int span = 0;
    int maxspan = 0;
    int hashTable[128];
    for (int i = 0; i < 128; ++i)
        hashTable[i] = 0;
    for(int i = 0; i < s.size(); ++i)
    {
        if (hashTable[s[i]] == 1)
        {
            span = i - beg;
            beg = i;
            hashTable[s[i]] == 0;
            if (span > maxspan)
                maxspan = span;
        }
        else
        {
            hashTable[s[i]] = 1;
        }
    }
    return maxspan;
}

int main()
{
    const string a = "abmadsefadd";
    const string a1 = "avoaid";
    cout << getMaxLen(a) << endl;
    cout << getMaxLen(a1) << endl;
}