secondsToHMS

#include <iostream>

int main()
{
    const int secondsInMinute{60};
    const int minutesInHour {60};
    const int secondsInHour {minutesInHour * secondsInMinute};

    int seconds {3675}; // good test case
    int minutes {0};
    int hours {0};

    std::cout << "Enter seconds:\n";
    std::cin >> seconds;

    hours = seconds / secondsInHour;
    seconds %= secondsInHour; // seconds = seconds % secondsInHour);

    minutes = seconds / secondsInMinute;
    seconds %= secondsInMinute; // seconds = seconds % secondsInMinute);

    std::cout << hours << " hour(s) " << minutes << " minute{s) " << seconds << " second(s)\n";
}