How to change vector inside map c++?

Question

C++ / C#

Hello, I'm interested in solving the following problem. I have a map> and I need to access a vector by its key and resize it. How can I do it?
map<string, vector<string>> SOURCE;

Answer 1

map<string, vector<string>> mymap;
string key = "asdf";

auto elem {mymap.find(key)};
if(elem != mymap.end())
{
  //...
  elem->second.resize(42);
}

...

в С++17 можно еще проще/по-другому.

Answer 2

I need to access a vector by its key and resize it. How can I do it?
SOURCE["key"].resize(new_size);