event_period_reverse

#include <vector>
#include <algorithm>
#include <iterator>
#include <iostream>
#include <sys/time.h>

void event(std::vector<char> &v, std::vector<unsigned long long> &sp, std::vector<unsigned long long> &ep)
{
    char pre_val(0), cur_val(0);
    unsigned long long pos(0);
    for (std::vector<char>::iterator i = v.begin(); i != v.end(); ++i)
    {
        cur_val = *i;
        if ((cur_val != pre_val) && (cur_val))
        {
            pos = std::distance(v.begin(), i);
            sp.push_back(pos);
            if (pre_val) ep.push_back(pos);
            pre_val = cur_val;
        }
    }
    ep.push_back(std::distance(v.begin(), v.end() - 1));
}

void period(std::vector<char> &v, std::vector<unsigned long long> &sp, std::vector<unsigned long long> &ep)
{
    char pre_val(0), cur_val(0);
    unsigned long long pos(0);
    for (std::vector<char>::iterator i = v.begin(); i != v.end(); ++i)
    {
        cur_val = *i;
        if (cur_val != pre_val)
        {
            pos = std::distance(v.begin(), i);
            if (cur_val) sp.push_back(pos);
            if (pre_val) ep.push_back(pos);
            pre_val = cur_val;
        }
    }
    if (cur_val) ep.push_back(std::distance(v.begin(), v.end() - 1));
}

int main()
{
    std::vector<char> v;
    std::vector<unsigned long long> sp, ep;
    timeval t1, t2;
    double elapsedTime;

    // Creation of events vector like [0 0 0 1 0 0 -1 0 0 -1 -1 1 0 0 0 1 0 0 1 -1 0 0 1]
    v.push_back(0); v.push_back(0);
    v.push_back(0); v.push_back(1);
    v.push_back(0); v.push_back(0);
    v.push_back(-1); v.push_back(0);
    v.push_back(0);
    v.push_back(-1); v.push_back(-1);
    v.push_back(1); v.push_back(0);
    v.push_back(0); v.push_back(0);
    v.push_back(1); v.push_back(0);
    v.push_back(0); v.push_back(1);
    v.push_back(-1); v.push_back(0);
    v.push_back(0); v.push_back(1);

    std::cout << "Input vector:\n";
    std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";

    // start timer
    gettimeofday(&t1, NULL);
    event(v, sp, ep);
    // stop timer
    gettimeofday(&t2, NULL);

    // compute and print the elapsed time in millisec
    elapsedTime = (t2.tv_sec - t1.tv_sec) * 1000.0;      // sec to ms
    elapsedTime += (t2.tv_usec - t1.tv_usec) / 1000.0;   // us to ms

    std::cout << "Event => sp: ";
    std::copy(sp.begin(), sp.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";
    std::cout << "Event => ep: ";
    std::copy(ep.begin(), ep.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";
    std::cout << "Event => elapsed time " << elapsedTime << " ms \n";

    std::vector<unsigned long long>().swap(sp);
    std::vector<unsigned long long>().swap(ep);

    // start timer
    gettimeofday(&t1, NULL);
    period(v, sp, ep);
    // stop timer
    gettimeofday(&t2, NULL);

    // compute and print the elapsed time in millisec
    elapsedTime = (t2.tv_sec - t1.tv_sec) * 1000.0;      // sec to ms
    elapsedTime += (t2.tv_usec - t1.tv_usec) / 1000.0;   // us to ms

    std::cout << "Period => sp: ";
    std::copy(sp.begin(), sp.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";
    std::cout << "Period => ep: ";
    std::copy(ep.begin(), ep.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";
    std::cout << "Period => elapsed time " << elapsedTime << " ms \n";

    return 0;
}