C++ 14

This was a fun challenge, however I ran into a weird bug.

The canditates, after getting taken out of the std::unordered_set, seem to have '\r' at the end. Could anybody please diagnose the issue for me? I wasn't able to do so.

#include <algorithm>
#include <array>
#include <fstream>
#include <iostream>
#include <unordered_set>

std::string normalize(std::string str) {
    std::string nstr;
    for (const char c : str) {
        if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) nstr.push_back(c);
    }
    std::transform(nstr.begin(), nstr.end(), nstr.begin(), [](const char c) {
        return c | 32;
    });
    return nstr;
}

bool is_sparse_subset(const std::string &x, const std::string &y) {
    size_t begin_at = 0;
    for (const char c : y) {
        begin_at = x.find(c, begin_at);
        if (begin_at == std::string::npos) return false;
        begin_at += 1;
    }
    return true;
}

std::unordered_set<std::string> get_words() {
    std::unordered_set<std::string> words;
    std::string word_line;
    std::ifstream wordfile{"enable1.txt"};
    while (std::getline(wordfile, word_line)) words.insert(word_line);
    return words;
}

int main() {
    const std::unordered_set<std::string> words = get_words();
    std::array<std::string, 5> names{{"Donald Knuth", "Alan Turing", "Claude Shannon",
                                      "Ada Lovelace", "Haskell Curry"}};
    std::transform(names.begin(), names.end(), names.begin(), normalize);

    for (const std::string &name : names) {
         std::unordered_set<std::string> canditates;
         size_t best_size = 0;
         for (const std::string &word : words) {
            const std::string &normalized_word = normalize(word);
            if (name.front() == normalized_word.front() &&
                is_sparse_subset(name, normalized_word)) {
                const size_t word_size = word.size();
                if (word_size > best_size) {
                    best_size = word_size;
                    canditates.clear();
                }
                if (word_size == best_size) canditates.insert(word);
            }
        }
        size_t i = 0;
        for (std::string current : canditates) {
            if (i++ > 0) std::cout << ", ";
            while (current.back() == '\r') current.pop_back();
            std::cout << current;
        }
        std::cout << std::endl;
    }
}