Find the sum of all highest occurring elements in an Array

Given an array of integers containing duplicate elements. The task is to find the sum of all highest occurring elements in the given array. That is the sum of all such elements whose frequency is maximum in the array.
Examples: 

Input : arr[] = {1, 1, 2, 2, 2, 2, 3, 3, 3, 3}
Output : 20
The highest occurring elements are 3 and 2 and their
frequency is 4. Therefore sum of all 3's and 2's in the 
array = 3+3+3+3+2+2+2+2 = 20.

Input : arr[] = {10, 20, 30, 40, 40}
Output : 80

Approach: 

• Traverse the array and use a unordered_map in C++ to store the frequency of elements of the array such that the key of map is the array element and value is its frequency in the array.
• Then, traverse the map to find the frequency of the max occurring element.
• Now, to find the sum traverse the map again and for all elements with maximum frequency find frequency_of_max_occurring_element*max_occurring_element and find their sum.

Below is the implementation of the above approach: 

C++

// CPP program to find the sum of all maximum
// occurring elements in an array

#include <bits/stdc++.h>
using namespace std;

// Function to find the sum of all maximum
// occurring elements in an array
int findSum(int arr[], int N)
{
    // Store frequencies of elements
    // of the array
    unordered_map<int, int> mp;
    for (int i = 0; i < N; i++)
        mp[arr[i]]++;


    // Find the max frequency
    int maxFreq = 0;
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        if (itr->second > maxFreq) {
            maxFreq = itr->second;
        }
    }

    // Traverse the map again and find the sum
    int sum = 0;
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        if (itr->second == maxFreq) {
            sum += itr->first * itr->second;
        }
    }

    return sum;
}

// Driver Code
int main()
{
    int arr[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3 };

    int N = sizeof(arr) / sizeof(arr[0]);

    cout << findSum(arr, N);

    return 0;
}

Java

// Java program to find the sum of all maximum
// occurring elements in an array
import java.util.*;

class GFG
{

// Function to find the sum of all maximum
// occurring elements in an array
static int findSum(int arr[], int N)
{
    // Store frequencies of elements
    // of the array
    Map<Integer,Integer> mp = new HashMap<>();
    for (int i = 0 ; i < N; i++)
    {
        if(mp.containsKey(arr[i]))
        {
            mp.put(arr[i], mp.get(arr[i])+1);
        }
        else
        {
            mp.put(arr[i], 1);
        }
    }

    // Find the max frequency
    int maxFreq = 0;
    for (Map.Entry<Integer,Integer> entry : mp.entrySet())
    {
        if (entry.getValue() > maxFreq)
        {
            maxFreq = entry.getValue();
        }
    }

    // Traverse the map again and find the sum
    int sum = 0;
    for (Map.Entry<Integer,Integer> entry : mp.entrySet())
    {
        if (entry.getValue() == maxFreq)
        {
            sum += entry.getKey() * entry.getValue();
        }
    }

    return sum;
}

// Driver Code
public static void main(String[] args)
{

    int arr[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3 };

    int N = arr.length;
    System.out.println(findSum(arr, N));
}
}

// This code is contributed by Princi Singh

Python3

# Python3 program to find the Sum of all maximum
# occurring elements in an array

# Function to find the Sum of all maximum
# occurring elements in an array
def findSum(arr, N):

    # Store frequencies of elements
    # of the array
    mp = dict()
    for i in range(N):
        mp[arr[i]] = mp.get(arr[i], 0) + 1


    # Find the max frequency
    maxFreq = 0
    for itr in mp:
        if (mp[itr] > maxFreq):
            maxFreq = mp[itr]


    # Traverse the map again and find the Sum
    Sum = 0
    for itr in mp:
        if (mp[itr] == maxFreq):
            Sum += itr* mp[itr]

    return Sum


# Driver Code

arr= [1, 1, 2, 2, 2, 2, 3, 3, 3, 3 ]

N = len(arr)

print(findSum(arr, N))

# This code is contributed by mohit kumar

C#

// C# program to find the sum of all maximum
// occurring elements in an array
using System;
using System.Collections.Generic;

class GFG
{

// Function to find the sum of all maximum
// occurring elements in an array
static int findSum(int []arr, int N)
{
    // Store frequencies of elements
    // of the array
    Dictionary<int,int> mp = new Dictionary<int,int>();
    for (int i = 0 ; i < N; i++)
    {
        if(mp.ContainsKey(arr[i]))
        {
            var val = mp[arr[i]];
            mp.Remove(arr[i]);
            mp.Add(arr[i], val + 1);
        }
        else
        {
            mp.Add(arr[i], 1);
        }
    }

    // Find the max frequency
    int maxFreq = 0;
    foreach(KeyValuePair<int, int> entry in mp)
    {
        if (entry.Value > maxFreq)
        {
            maxFreq = entry.Value;
        }
    }

    // Traverse the map again and find the sum
    int sum = 0;
    foreach(KeyValuePair<int, int> entry in mp)
    {
        if (entry.Value == maxFreq)
        {
            sum += entry.Key * entry.Value;
        }
    }

    return sum;
}

// Driver Code
public static void Main(String[] args)
{

    int []arr = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3 };

    int N = arr.Length;
    Console.WriteLine(findSum(arr, N));
}
}

// This code is contributed by Rajput-Ji

Javascript

<script>

// JavaScript program to find
// the sum of all maximum
// occurring elements in an array

// Function to find the sum of all maximum
// occurring elements in an array
function findSum(arr,N)
{
    // Store frequencies of elements
    // of the array
    let mp = new Map();
    for (let i = 0 ; i < N; i++)
    {
        if(mp.has(arr[i]))
        {
            mp.set(arr[i], mp.get(arr[i])+1);
        }
        else
        {
            mp.set(arr[i], 1);
        }
    }

    // Find the max frequency
    let maxFreq = 0;
    for (let [key, value] of mp.entries())
    {
        if (value > maxFreq)
        {
            maxFreq = value;
        }
    }

    // Traverse the map again and find the sum
    let sum = 0;
    for (let [key, value] of mp.entries())
    {
        if (value == maxFreq)
        {
            sum += key * value;
        }
    }

    return sum;
}

// Driver Code

let arr=[ 1, 1, 2, 2, 2, 2, 3, 3, 3, 3 ];
let N = arr.length;
document.write(findSum(arr, N));


// This code is contributed by patel2127

</script>

Output:

20

Time Complexity: O(N), where N is the number of elements in the array.

Auxiliary Space: O(N) because it is using unordered_map