https://leetcode.com/problems/longest-substring-without-repeating-characters/

gistfile1.cpp

#include <vector>
#include <iterator>

int lengthOfLongestSubstring(string s) {
    vector <char> alph;
    char ch{};
    int count{};
    int max_count{};
    for(size_t i=0; i<s.size(); ++i)
    {
        ch = s[i];
        auto it = find(alph.begin(),alph.end(),ch);
        if( it != alph.end())
        {
            count=count-distance(alph.begin(),it);
            alph.erase(alph.begin(),++it);
            alph.push_back(ch);
        }
        else
        {
            alph.push_back(ch);
            count++;
            if(max_count < count) max_count=count;
        }

    }
    return max_count;
}
};