Containers (map)

Question 1

How can you insert a new element in a map, and how do you know if the operation was succesful?

Answer 1

auto [It, success] = m_map.insert({23, "Value"});
cout << "Operation " << (success ? "Success" : "Failed") << "\n";

It is the position where the elemet was inserted.

Question 2

how do you know if a element was inserted into a map, using a Position as a reference?

Answer 2

auto Iti = m_map.insert(it, {23, "Value"});
cout << "Operation " << (it != m_map.end() ? "Success" : "Failed") << "\n";

Question 3

On a map<K,V>, What is the difference beteween operator[] and insert

Answer 3

operator[] create a new element (empty) if the key doesnt exist menwhile insert doesn´t perform the operation.

The sintaxys of operator[] is:
T& = operator[cosnt Key&]

The sintaxys of insert is:
[iterator, bool] = insert( const value_type& value )

Question 4

Over a map, whai is the difference between insert and insert_or_assign

Answer 4

insert doesn’t replace the value if the key is already inserted but insert_or_assigndoes it.

Both of them return a pair with the iterator and operation result:
std::pair<iterator, bool>

Question 5

Which method do you use to find the firt elemetn that is greater than key?

Answer 5

Iterator upper_bound(const Key& key)

This operation can be considereted as:
Find the firt element that It > key

Complexity: O(log n)

Question 6

Which method do you use to find the firt elemetn that is not less than key?

Answer 6

iterator lower_bound(const Key& key)

This operation can be considereted as:
Find the firt element that It >= key

Complexity: O(log n)

Question 7

How do equal_range(x) work?

Answer 7

having a collection of elements, with their respective keys, equal_range will find the range where the key x is locates in the range [Rb, Re).

**This description asume that x is located in the map, but if not, the range will be something like:

a) for x < begin(): range will be [Rb, Rb)
b) for x >= end(): range will be [Re,)

For example:
```cpp
map<int, string> m_map {{1,”1”}, {2,”2”}, {3,”3”} ,{4,”4”} ,{5,”5”} ,{6,”6”} ,{7,”7”}}
auto rng = m_map.equal_range(x);
~~~

For x=4, the range will be: [4,5) wich means 4 >= 4 && 4 < 5

For x=-2, the range will be: [1,1) wich means -2 >= 1 && -2 < 1