Competitive Programming in C++: The Keys to Success/

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STL

STL

We'll cover the following...

Library

As briefly mentioned before, there are 3 variants of Balanced BST in STL that we are particularly interested in:

  1. Set

  2. MultiSet

  3. Map

Include statement:

#include <set>

#include <multiset>

#include <map>

Set

The Set is a container that stores unique elements following a specific order.

Below are the operations we’ll be using frequently. For complete documentation check here.

set<int> S; // empty set
bool x = S.empty(); // to check if set is empty
int sz = S.size(); // get size of set
S.insert(x); // Insert integer x into the set
S.erase(x); // Remove integer x from the set
S.erase(it); // Iterator version of erase
set<int>::iterator it = S.find(x); // Returns iterator to element with passed value if exists else return iterator to S.end()

Since a set only has unique elements, adding duplicate elements doesn’t have any effect.

Multiset

Multiset elevates the limitation with Set, we can have duplicate elements in a multiset.

Below are the operations we’ll be using frequently. For complete documentation check here.

multiset<int> S; // empty multiset
bool x = S.empty(); // to check if multiset is empty
int sz = S.size(); // get size of multiset
S.insert(x); // Insert integer x into the multiset
S.erase(x); // Remove integer x from the multiset
S.erase(it); // Iterator version of erase
multiset<int>::iterator it = S.find(x); // Returns iterator to element with passed value if exists else return iterator to S.end()

The Iterator version of erase() should be used when dealing with multiset. The non-iterator version ...