I have map with strings as keys and vectors as values:
map<string,vector<int>> myMap;
//("key", value):
("a", {1})
("b", {2,3})
("c", {1})
("d", {1})
("e", {2,3})
Is it possible to get keys based on their values? I want the keys that have the same value i.e (a,c,d) and (b,e).
You have to look at every element
std::vector<std::string> keys_matching(const std::map<std::string, std::vector<int>> & map, const std::vector<int> & value) {
std::vector<std::string> result;
for (auto & [k, v] : map) {
if (v == value) {
result.push_back(k);
}
}
return result;
}
using Data = std::map<std::string, std::vector<int>>;
using ReversedData = std::unordered_map<int, std::vector<std::string>>;
ReversedData reverseValues(const Data& d)
{
ReversedData r;
for (const auto &[key, vec] : d) {
for (auto x : vec) r[x].push_back(key);
}
return r;
}