Найти непрерывный участок последовательности

#include <vector>
#include <algorithm>
#include <iostream>
#include <iterator>
#include <time.h>
int random()
{
    return rand()%100-50;
}
 
struct Summator {
    Summator() { sum = 0; }
    int operator()(int n) { sum += n; return sum; }
    Summator &operator=(const Summator &ob) { sum = ob.sum; return *this; }
    bool operator==(int n) { return sum == n ? true : false; }
    int sum;
};
 
int main()
{
    srand(time(NULL));
    std::vector<int> cont(200);
    std::generate(cont.begin(), cont.end(), random);
    std::copy(cont.begin(), cont.end(), std::ostream_iterator<int>(std::cout," "));
    std::vector<int>::iterator first, last;
    std::cout << "\n" << "Result: " << "\n";
    for(first = cont.begin() ; first != cont.end() ; ++first)
        for(last = first ; last != cont.end() ; ++last)
        {
            if(std::for_each(first, last, Summator()) == 0 && first != last)
            {
                std::cout << "Sequence: ";
                std::copy(first, last, std::ostream_iterator<int>(std::cout, " "));
                std::cout << "\n\n";
            }
        }
    return 0;
}

std::for_each(first, last, Summator())

std::accumulate(first, last, 0)