Currently the most widely used collection of collections in C ++

I am looking for a set of containers in C ++. I want something where I could add elements, but they would not be repeated more than once, and the search in this collection would be O (1). For this, the container for the defacto cross-compiler is now used. I saw some in boost (e.g. mpl), and there is one in the future C ++ standards, but what is the best use now and here?

EDIT

An example of saving a vector in a boost :: unordered_set container. So for me it seems to fit my needs, but I will have a lot of data, so if someone immediately sees some potential error, you can comment on what could go wrong. Again, all elements will be sorted by vector without pointers.

vector<string> values1;
values1.push_back("aaa");
values1.push_back("bbb");
values1.push_back("ccc");

vector<string> values2;
values2.push_back("aa");
values2.push_back("bbb");
values2.push_back("ccc");

vector<string> values3;
values3.push_back("aaa");
values3.push_back("bbb");

vector<string> values4;
values4.push_back("aaa");
values4.push_back("bbb");
values4.push_back("ccc");
values4.push_back("ddd");

vector<string> values5;
values5.push_back("aaa");
values5.push_back("bbb");
values5.push_back("ccc");


vector<string> values6;
values6.push_back("aaa");
values6.push_back("bbb");
values6.push_back("ccc");
values6.push_back("ddd");

boost::unordered_set<vector<string> > collection;
collection.insert(values1); // 1
cout << collection.size() << endl;
collection.insert(values2); // 2
cout << collection.size() << endl;
collection.insert(values3); // 3
cout << collection.size() << endl;
collection.insert(values4); // 4
cout << collection.size() << endl;
collection.insert(values5); // 4
cout << collection.size() << endl;
collection.insert(values6); // 4
cout << collection.size() << endl;