The document discusses the C++ Standard Template Library (STL) unordered_set and set containers. [1] The unordered_set stores unique elements in no particular order, allowing fast retrieval with average O(1) time complexity for search, insertion, and removal. [2] The set stores unique elements in a particular order determined by a comparison function, with average O(logN) time complexity for search, insertion, and removal.

1. Level up your coding skills with
the C++ Standard Template
Library (STL):
Sets
BY JOYJIT CHOUDHURY

2. Unordered Set
 The unordered_set is a container that stores unique
elements in no particular order. It allows fast retrieval of
individual elements based on their value.
 It is typically implemented as a hash table, where the
value of the element is also it’s key
 Search, insertion, and removal have an average time
complexity of O(1)
 Defined in the header <unordered_set>
 Belongs to the namespace std
(remember : using namespace std)

3. Insertion of elements
uSet
uSet.insert(12);
uSet
12
uSet
12
uSet.insert(24);
24

4. Insertion of elements
uSet
12
uSet.insert(24);
24
uSet
12 24
uSet
12 24
uSet.insert(12);
uSet.insert(36);
uSet
12 24
36

5. Remove elements
uSet.erase(24);
uSet
12 24
36
uSet
12
36
Remove elements
uSet
12
uSet
12
uSet
12
uSet.erase(36);

7. Search for an element
 Member function find(), searches the container for an
element with a particular value. If such an element exists, it
returns an iterator to that element. Otherwise it returns an
iterator to unordered_set::end (the element past the end of
the container)
 Another function count(), can be used to check whether
an element exists or not. It returns 1, if the desired element
exists, otherwise it returns 0

9. Number of elements
 Member function size(), returns the number of elements in the unordered set

10. Is it empty?
 Member function empty(), returns true if the unordered set is empty, false
otherwise

11. Set
 The set is a container that stores unique elements in a particular
order. Sorting is done using the comparison function compare
 It is typically implemented as a balanced binary search tree, where
the value of the element is also it’s key
 Search, insertion, and removal have an average time complexity of
O(logN)
 Defined in the header <set>
 Belongs to the namespace std
(remember : using namespace std)

12. Set
 Search, insertion, and removal of elements with respect to set can
be done in the same way as that for unordered_set using the
functions insert(), erase(), find().
 The difference being, the different time complexities of these
operations with respect to the different containers
O(1) : unordered_set vs. O(logN) : set
 Member functions size(), empty() also perform the same actions for
set as they do for unordered_set
 The elements in set are stored in a particular order and allow range
based iterations, whereas unordered_set stores the elements in a
random order

17.  That’s not all. There are many other functions
and techniques that could come in handy.
Read about them on cplusplus.com or
cppreference.com or somewhere else. Just
google it !