#include <algorithm>
#include <fstream>
#include <iostream>
#include <iterator>
#include <numeric>
#include <vector>

int hamming_distance(std::string a, std::string b)
{
    if (a.size() > b.size())
        std::swap(a, b);

    int distance {
        std::inner_product(std::begin(a), std::end(a),
                           std::begin(b), 0,
                           std::plus<int>{},
                           [](char a, char b) { return a != b; })
    };

    return distance + (b.size() - a.size());
}

int main()
{
    std::ifstream ifs { "wordlist.txt" };

    std::vector<std::string> wordlist { 
        std::istream_iterator<std::string>{ ifs },
        std::istream_iterator<std::string>{ }
    };

    std::cout << "Enter your word: ";

    std::string word { };
    std::cin >> word;
    
    auto it = std::next(std::begin(wordlist), 5);
    std::partial_sort(std::begin(wordlist), std::end(wordlist), it,
              [&word](std::string const& a, std::string const& b)
              {
                  int hamming_a { hamming_distance(a, word) };
                  int hamming_b { hamming_distance(b, word) };
                  return hamming_a < hamming_b;
              });

    std::cout << "The five closest words are: " << std::endl;
    std::copy(std::begin(wordlist), it, std::ostream_iterator<std::string>{ std::cout, "\n" });
}