#include <iostream>
#include <numeric>
#include <vector>
#include <cstdlib>
#include <cstring>

// note: for c++20 `std::vector<std::string> &a` needs to be `std::vector<std::string> &&a`
int main()
{
    std::string pathstr="/bin:/usr/bin:/usr/local/bin";
    auto paths = std::accumulate(pathstr.begin(), pathstr.end(),
            std::vector<std::string>(),
            [](std::vector<std::string> &a, const char &b)
                    -> std::vector<std::string>&
            {
                auto new_elem = [&a](const char *p)
                {
                    a.emplace_back();
                    auto count = strcspn(p,":");
                    //std::cerr << "reserving " << count << " bytes (with +1 for null)" << std::endl;
                    a.back().reserve(count+1);
                };
                if(!a.size())
                    new_elem(&b);
                if(':'==b)
                    new_elem(&b+1);
                else
                    a.back() += b;
                return a;
            });
            
    for(auto &path : paths)
        std::cout << path << std::endl;
    return 0;
}