How to Find the Frequency of an Element in a Set in C++?

C++ STL provides a set container that can be used to store unique elements in a sorted order. In this article, we will learn how to find the frequency of an element in a set in C++.

Example:

Input:
set<int>s ={10,20,30,40,50}

Output:
Frequency of 30 is 1

Finding Frequency of an Element in a Set in C++

In C++, the set stores the unique element, so if the element is present in the set, its frequency cannot be more than 1. But std::set still has the std::set::count() function that can be used to find the frequency of a specific element. This function returns 0 if the element is not present and 1 if the element is present.

C++ Program to Find the Frequency of an Element in a Set

The below example demonstrates how we can find the frequency of a specific element in a set.

C++

// C++ program to illustrate how to find the frequency of a
// specific element in a set
#include <algorithm>
#include <iostream>
#include <set>
using namespace std;

int main()
{

    // Intializing a  set with few elements
    set<int> mySet = { 10, 20, 30, 20, 40, 20, 50 };

    // Print the elements of the set
    cout << "Set Elements: ";
    for (auto it : mySet) {
        cout << it << " ";
    }
    cout << endl;

    // Choose target element
    int targetElement = 30;

    // Use the count function to find the frequency of the
    // target element
    int frequency = mySet.count(targetElement);

    // Output the frequency of the target element
    cout << "Frequency of " << targetElement
         << " is: " << frequency << endl;

    return 0;
}

Output

Set Elements: 10 20 30 40 50 
Frequency of 30 is: 1

Time Complexity: O(N), where N is the total number of elements in the set.
Auxiliary Space: O(1)