Answers for "what does std unique do"

remove duplicates from vector c++

sort( vec.begin(), vec.end() );
vec.erase( unique( vec.begin(), vec.end() ), vec.end() );

insert only unique values into vector

std::vector<std::string> name;

....
if (std::find(name.begin(), name.end(), someName) == name.end()) {
  // someName not in name, add it
  name.push_back(someName);
}