Embercode: AI-powered software engineer course

1. What does this print? ``

cpp
std::map<std::string, std::vector<int>> g;
g["b"].push_back(1);
g["a"].push_back(2);
g["b"].push_back(3);
std::cout << g.size() << ' ' << g.begin()->first << ' ' << g["b"].size();

``

2 b 23 a 22 a 22 a 1

2. What does this print? ``

cpp
std::map<std::string, std::vector<int>> g;
g["Pune"].push_back(1);
std::cout << g.count("Goa") << ' ' << g.size() << ' ';
std::cout << g["Goa"].size() << ' ' << g.size();

``

0 1 0 20 1 1 21 1 0 10 1 0 1

3. A program groups orders by city like this, where Order is the struct from the lesson. ``

cpp
std::map<std::string, Order> byCity;
for (const Order& o : orders) {
    byCity[o.city] = o;
}

`` Two orders are for Pune. What goes wrong?

The loop does not compile, because a map cannot hold a struct as its valueThe map gets two Pune entries, one for each order, so its size doublesThe brackets return a copy, so the orders are never stored in the mapThe second Pune order replaces the first, so only one Pune order is kept; the value should be a vector that grows with push_back

4. Which method of std::multimap returns a pair of iterators that cover every entry for one key? Write its name only.

Type your answer.

5. Which std::map method throws std::out_of_range when the key is missing? Write its name only.

Type your answer.

Grouping