Frequency analysis

freq_analyser.cc

#include <iostream>
#include <fstream>
#include <string>
#include <cctype>
 
struct elem
{
    elem (char c): c (c), count (0), link (nullptr) {};
   
    char c;
    unsigned int count;
    elem* link;
};
 
 
int main ()
{
    std::string filename;
    std::cin >> filename;
 
    std::ifstream fin (filename);

    if (!fin.good ()) return -1;
   
    elem* first = new elem (fin.get ());
    first -> count = 1;
   
    while (fin.good ())
    {
        char ch = fin.get ();

            elem* current = first;
            for (current = first; current -> c != ch; current = current -> link)
            {
                if (current -> link == nullptr)
                {
                    elem* next = new elem (ch);
                    current -> link = next;
                }
            }

            current -> count += 1;
    }


    for (elem* cnt = first; cnt != nullptr; cnt = cnt -> link)
    {
        for (elem* current = first; current -> link != nullptr; current = current -> link)
        {
            if (current -> count < current -> link -> count)
            {
                char temp_c = current -> c;
                unsigned int temp_count = current -> count;
                
                current -> c = current -> link -> c;
                current -> count = current -> link -> count;

                current -> link -> c = temp_c;
                current -> link -> count = temp_count;
            }
        }
    }

    for (elem* current = first; current != nullptr; current = current -> link)
        std::cout << current -> c << '\t' << (int) (current -> c) << '\t' << current -> count << std::endl;
   
 
    return 0;
}