# Solved: vector unique in

As a C++ programmer, I am excited to talk about one of the language’s unique features – the vector container, specifically the utility and usage of the ‘unique’ function in a vector. This powerful component of the C++ Standard Template Library (STL) streamlines data organization and simplifies our coding efforts. Making good use of vector unique function can exponentially increase the efficiency of your program.

The ‘unique’ function primarily eliminates consecutive duplicates in a given range defined by container like a vector, and returns an iterator pointing to the next of the final distinct element left.
Understanding vectors in C++ and the ‘unique’ function is essential for anyone who wants to become proficient in this programming language.

#include
#include
#include

int main()
{
std::vector vec = {10, 20, 20, 30, 30, 30, 20, 20, 10};

std::sort(vec.begin(), vec.end());

std::vector::iterator ip;

ip = std::unique(vec.begin(), vec.end());

vec.resize(std::distance(vec.begin(), ip));

for (ip = vec.begin(); ip != vec.end(); ip++) {
std::cout << *ip << " "; } return 0; } [/code]

## Explanation of the C++ Code:

The code first includes the necessary headers – the iostream for input/output operations, vector for using the vector data structure, and algorithm for accessing the ‘unique’ function. It then declares a vector ‘vec’ of integers and initializes it with random numbers.

The ‘sort’ function arranges the elements in ascending order. Sorting is important because the ‘unique’ function only removes consecutive duplicates. If the duplicates aren’t next to each other, they won’t be removed.

The ‘unique’ function is then used, with the range being the beginning and end of ‘vec’. ‘Unique’ returns an iterator that points to the end of the range without duplicates.

## Role of Vector and ‘Unique’ method:

The output of the above code will be “10 20 30”. As we can observe, all the duplicate values are removed, and only unique values remain. Point to be noted here, ‘unique’ function does not delete the duplicate elements, it returns an iterator to the next of the last unique elements and not beyond that, and the value remains undefined.

The line ‘vec.resize(std::distance(vec.begin(), ip))’ is to remove the undefined elements and resize the vector according to the unique values. Our final vector has no duplicates now. The ‘for’ loop prints out the final vector.

## Utilization of Libraries and Functions:

Using the STL libraries, such as vector and algorithm, not only saves time in coding but also provides efficient and easy-to-understand solutions for complex tasks. The ‘unique’ function in vectors is a prime example. It keeps the original order, removes consecutive duplicates and makes it easier for us to manage data. This comes in very handy, especially when dealing with large data sets.

Therefore, understanding and making good use of these predefined libraries and functions is an essential skill for every C++ programmer.

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