Which required fields are missing
A form submission arrives as a bag of strings and the server checks it before touching the database.
- A field is missing when its key is absent, or its value is empty or only whitespace.
- Report them in the order the requirements were given, not the order the payload happens to be in.
- Nothing required means nothing missing.
missingFields(payload: map<string, string>, required: list<string>) → list<string>
C++ needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
std::vector<std::string> missingFields(std::map<std::string, std::string> payload, std::vector<std::string> required) {
}Worked examples
| Call | Result |
|---|---|
missingFields(std::map<std::string, std::string>{{std::string("name"), std::string("Ada")}, {std::string("email"), std::string("")}}, std::vector<std::string>{std::string("name"), std::string("email"), std::string("phone")}) | std::vector<std::string>{std::string("email"), std::string("phone")} |
missingFields(std::map<std::string, std::string>{{std::string("name"), std::string(" ")}}, std::vector<std::string>{std::string("name")}) | std::vector<std::string>{std::string("name")} |
missingFields(std::map<std::string, std::string>{{std::string("name"), std::string("Ada")}}, std::vector<std::string>{std::string("name")}) | std::vector<std::string>{} |
missingFields(std::map<std::string, std::string>{}, std::vector<std::string>{}) | std::vector<std::string>{} |
Hint
Walk the requirements, not the payload — that is what fixes the output order.
Reference solution in C++
std::vector<std::string> missingFields(std::map<std::string, std::string> payload, std::vector<std::string> required) {
std::vector<string> result;
for (const auto& key : required) {
auto it = payload.find(key);
if (it == payload.end()) { result.push_back(key); continue; }
string v = it->second;
size_t a = v.find_first_not_of(" \t\n\r");
if (a == string::npos) result.push_back(key);
}
return result;
}