Functions in C++ Standard Template Library (STL) Overview Containers, algorithms, and iterators Offers predefined and efficient data structures and algorithms Vector and Array Operations Declare, manipulate, and print vectors using iterators and loop functions Vector Declaration vector vec; Vector Manipulation Insert: vec.push_back(value) Access: vec[index] Size: vec.size() Vector Printing Using iterators: for (vector::iterator it = vec.begin(); it != vec.end(); ++it) { cout << *it << " "; } Other Container Data Structures List, deque, stack, queue, priority queue, set Key Properties List: Doubly linked list Deque: Double-ended queue Stack: Last-in-first-out (LIFO) Queue: First-in-first-out (FIFO) Priority queue: Element with highest priority is removed first Set: Stores only unique elements, keeps elements sorted Deleting and Inserting Elements Erase: vec.erase(position) or vec.erase(range.begin(), range.end()) Insert: vec.insert(position, value) Vector Iterators Provide a way to traverse and access vector elements Types: vector::iterator, vector::const_iterator Dictionary Order Sequences Items are ordered based on their values Used in associative containers like set and map Skeleton of a C++ Code #include using namespace std;

int main() { // Code here return 0; } Using Namespace std Brings all standard library elements into the current scope Use using namespace std; to enable it Utility Library: Pair Store two elements of different types Create: pair<type1, type2> name(value1, value2) Bit Manipulation: Built-in Popcount Function Counts the number of set bits in an integer Use popcount(number) Iterators for Set and Other Containers Set iterators: set::iterator, set::const_iterator Access and manipulate elements in a set Map and Unordered Map Implement key-value pairs Map: Stores elements in a sorted order (dictionary order) Unordered map: Stores elements in an unsorted order (hash table) Vectors as a Container Dynamic array implementation Efficient storage and manipulation Algorithms: Sorting, Partial Sorting, Custom Comparison Sort: sort(vec.begin(), vec.end()) Partial sort: partial_sort(vec.begin(), vec.end(), n) Custom comparison: Pass a function as an argument to sort Unique Characteristics of Set Only unique elements are stored Elements are kept sorted Vector Iterators Overview STL provides various types of iterators to traverse and manipulate the elements of different containers. Vector iterators are a type of random-access iterator that can be used to access the elements of a vector. Declaring Vector Iterators To declare a vector iterator, use the following syntax: vector vect; vector::iterator it; it = vect.begin(); Manipulating Vector Elements using Iterators Use the following functions to manipulate vector elements using iterators: it = vect.begin() : returns an iterator pointing to the first element of the vector. it = vect.end() : returns an iterator pointing to the theoretical end of the vector. it++ or ++it : moves the iterator to the next element. it-- or --it : moves the iterator to the previous element. *it : dereferences the iterator to access the element it points to. it1 = it2 + n : moves the iterator it1 n positions ahead of it2. it1 = it2 - n : moves the iterator it1 n positions behind it2. Printing Vector Elements using Iterators To print the elements of a vector using iterators, use the following code snippet: vector vect; for(vector::iterator it = vect.begin(); it != vect.end(); it++) { cout << *it << " "; } Deleting and Inserting Elements using Iterators Use the following functions to delete and insert elements at specific positions in a vector: it = vect.erase(it) : deletes the element pointed to by the iterator and returns an iterator pointing to the next element. vect.insert(it, value) : inserts a new element with the specified value before the element pointed to by the iterator. Vector Iterators in Comparison to Set Iterators Vector iterators are random-access iterators, which allow for faster traversal and manipulation of elements compared to set iterators, which are bidirectional iterators. However, set iterators provide faster lookup and insertion due to the inherent structure of the set data structure. References "Iterators - C++ Reference" "Vector Iterator - C++ Reference" "Set Iterator - C++ Reference"