How to Find the Mode of Numbers in an Array in C++?
Last Updated :
14 Feb, 2024
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Mode of any dataset is the item that occurs most frequently in it. In this article, we will find the mode of numbers in an unsorted array in C++.
For Example,
Input: myArray = { 1, 2, 3, 4, 5, 2, 3, 2, 2, 4, 2 } Output: Mode : 2
Finding Mode of Array Elements in C++
To find the mode of the array elements, we need to count the frequency of all elements in the array. To do that, we can use the std::unordered_map container where the key will represent the array element and its value will represent its frequency.
Approach
- Create an unordered_map of <int, int>.
- Start traversing the array.
- Now, if the array element is present in the unordered_map, increment its value.
- If the array element is not present, add the array element as key with value 1.
- Finally, use std::max_element algorithm to find the maximum frequency and hence mode of the numbers.
C++ Program to Find Mode of Array Elements
// C++ program to find the mode of an array
#include <algorithm>
#include <iostream>
#include <unordered_map>
using namespace std;
// Function to find the mode of an array
int findMode(int arr[], int n)
{
// Create a frequency map to count occurrences of each
// element
unordered_map<int, int> freqMap;
for (int i = 0; i < n; i++) {
freqMap[arr[i]]++;
}
// Find the element with the maximum frequency
auto maxElement
= max_element(freqMap.begin(), freqMap.end(),
[](const auto& a, const auto& b) {
return a.second < b.second;
});
// Return the mode (element with maximum frequency)
return maxElement->first;
}
int main()
{
// Test array
int arr[] = { 2, 2, 3, 3, 3, 4 };
int n = sizeof(arr) / sizeof(arr[0]);
// Find and print the mode of the array
cout << "Mode of the array is " << findMode(arr, n)
<< endl;
return 0;
}
Output
Mode of the array is 3
Time Complexity: O(n)
Auxiliary Space: O(n)
