C++ задача по контейнерам

Функция FindDocuments теперь должна выглядеть так:
vector<pair<int, int>> FindDocuments(
const map<string, set<int>>& word_to_documents,
const set<string>& stop_words,
const string& query);
Создайте map<int, int> document_to_relevance для хранения релевантности по идентификатору документа.
код:

using namespace std;

string ReadLine() {
string s;
getline(cin, s);
return s;
}

int ReadLineWithNumber() {
int result;
cin >> result;
ReadLine();
return result;
}

vector<string> SplitIntoWords(const string& text) {
vector<string> words;
string word;
for (const char c : text) {
if (c == ' ') {
words.push_back(word);
word = "";
} else {
word += c;
}
}
words.push_back(word);

return words;
}

set<string> ParseStopWords(const string& text) {
set<string> stop_words;
for (const string& word : SplitIntoWords(text)) {
stop_words.insert(word);
}
return stop_words;
}

vector<string> SplitIntoWordsNoStop(const string& text, const set<string>& stop_words) {
vector<string> words;
for (const string& word : SplitIntoWords(text)) {
if (stop_words.count(word) == 0) {
words.push_back(word);
}
}
return words;
}

void AddDocument(map<string, set<int>>& word_to_documents,
const set<string>& stop_words,
int document_id,
const string& document) {
for (const string& word : SplitIntoWordsNoStop(document, stop_words)) {
word_to_documents[word].insert(document_id);
}
}

vector<int> FindDocuments(const map<string, set<int>>& word_to_documents,
const set<string>& stop_words,
const string& query) {
const vector<string> query_words = SplitIntoWordsNoStop(query, stop_words);
set<int> document_ids;
for (const string& word : query_words) {
if (word_to_documents.count(word) == 0) {
continue;
}
for (const int document_id : word_to_documents.at(word)) {
document_ids.insert(document_id);
}
// А лучше так:
// const auto& local_document_ids = word_to_documents.at(word);
// document_ids.insert(local_document_ids.begin(), local_document_ids.end());
}

return {document_ids.begin(), document_ids.end()};
}


int main() {
const string stop_words_joined = ReadLine();
const set<string> stop_words = ParseStopWords(stop_words_joined);

// Read documents
map<string, set<int>> word_to_documents;
const int document_count = ReadLineWithNumber();
for (int document_id = 0; document_id < document_count; ++document_id) {
AddDocument(word_to_documents, stop_words, document_id, ReadLine());
}

const string query = ReadLine();
for (auto [document_id, relevance] : FindDocuments(word_to_documents, stop_words, query)) {
cout << "{ document_id = "s << document_id << ", relevance = "s << relevance << " }"s << endl;
}
}