main.cpp

#include <iostream>
#include <string>

bool nextPermutationStr(std::string& s)
{
    int sumIndex = 0;
    while (s[sumIndex] == 122)
    {
        ++sumIndex;
        if (sumIndex == s.length())
            return false;
    }

    ++s[sumIndex];
    for (int i = 0; i < sumIndex; ++i)
        s[i] = 97;

    return true;
}

int main()
{
    std::string passwordTarget = "kgpggr";
    std::string passwordStart = "aaaaaa";

    do
    {
        if (passwordStart == passwordTarget)
            std::cout << "Password cracked: " << passwordTarget << std::endl;
    } while (nextPermutationStr(passwordStart));

    return 0;
}