Собрание библиотек (STL, Boost и пр.) или ручками писать?

#include <iostream>
#include <map>
#include <intrin.h>
void main()
{
 
    unsigned __int64 start(0), finish(0), start1(0), finish1(0);
    int i;
    float f;
    char str[51] = "it is the first variant of individual task on spro";
    std::cout<<"Sentence:\n"<<str;
    std::cout<<"\n\n================================================================================\nResult:\n\n";
 
    //======================= STL =======================\\
 
    std::map<char,int>mp;
    std::map<char,int>::iterator wi;
    start=__rdtsc();
    for(i = 0; i < 51; ++i)
        mp[str[i]]++;
    finish = __rdtsc();
    for (wi = mp.begin(); wi != mp.end(); ++wi)
    {   
        f = (float)wi->second / 51;
        std::cout<<"Character "<<wi->first<<" meets with frequency "<<f<<std::endl;
    }
    std::cout<<"\nTime:\t"<<finish-start<<std::endl;
    //===================================================\\
 
    std::cout<<"\n================================================================================\n";
 
    //===================== My Code =====================\\
 
    int mas[256] = {0};
    start1 = __rdtsc();
    for(i = 0; i < 51; ++i)
        mas[(int)str[i]]++;
    finish1 = __rdtsc();
    for(i = 0; i < 256; ++i)
        if(mas[i])
        {
            f=(float)mas[i] / 51;
            std::cout<<"Character "<<(char)i<<" meets with frequency "<<f<<std::endl;
        }
    std::cout<<"\nTime:\t"<<finish1-start1<<std::endl;
    //===================================================\\
 
    system("pause");
}