#include <iostream>
#include <fstream>
#include <algorithm>
#include <iterator>
#include <map>
#include <sstream>
#include <memory>

int main()
{
    std::ifstream input("C:\\arm250\\asd.txt", std::ios::binary);

    std::map<char, std::map<char, int>> charactersMap;
    auto prevValue = std::make_pair(false, char());

    std::for_each(
        std::istreambuf_iterator<char>(input),
        std::istreambuf_iterator<char>(),
        [&](char in)
    {
        if (prevValue.first)
        {
            auto frequencyMap = &charactersMap[prevValue.second];
            int freqCount = (*frequencyMap)[in];
            (*frequencyMap)[in] = ++freqCount;
        }
        else charactersMap.insert(std::make_pair(in, std::map<char, int>()));

        prevValue = std::make_pair(true, in);
    });

    std::transform(std::begin(charactersMap), std::end(charactersMap), std::ostream_iterator<std::string>(std::cout, ""),
        [](std::pair<char, std::map<char, int>> freq)
    {
        std::stringstream output;
        int characterTotal = 0;
        std::for_each(std::begin(freq.second), std::end(freq.second),
            [&](std::pair<char, int> freqChar)
        {
            output << freq.first << "->" << freqChar.first << ": " << freqChar.second << std::endl;
            characterTotal += freqChar.second;
        });
        output << freq.first << ": " << characterTotal << std::endl;
        return output.str();
    });
}