How to Find the Unique Elements in an Array in C++?

In C++, an array is a data structure that is used to store multiple values of similar data types in a contiguous memory location. In this article, we will learn how to find the unique elements in an array in C++.

Example:

Input:
array = {1, 2, 1, 2, 2, 3, 4}

Output:
Unique elements in the array:  1 2 3 4

Find the Unique Elements in an Array in C++

To find the Unique elements in a std::array in C++, we can iterate through the array and store the array elements in a std::set because the set will store the unique elements of the array and ignore the duplicate values.

C++ Program to Find Unique Elements in an Array

The below program demonstrates how we can find the unique elements in an array in C++.

C++

// C++ Program to illustrate how to find unique elements in
// an array
#include <iostream>
#include <set>
#include <vector>
using namespace std;

// driver code
int main()
{
    vector<int> arr = { 1, 2, 1, 2, 2, 3, 4 };
    set<int> s;

   // inserting elements in the set.
    s.insert(arr.begin(), arr.end());
    cout << "Unique elements in the array: ";
    for (auto it = s.begin(); it != s.end(); ++it)
        cout << ' ' << *it;

    return 0;
}

Output

Unique elements in the array:  1 2 3 4

Time Complexity: O(N * log(N)), where N is the number of elements in the set.
Auxiliiary Space: O(N)