Number of subsets whose mean is maximum

Given an array arr[] of size N, the task is to count the number of subsets of arr[] whose mean is maximum.

Examples:

Input: arr[] = {1, 2, 1, 2}
Output: 3
Subsets with maximum mean are {2}, {2} and {2, 2}.

Input: arr[] = {1}
Output: 1

Approach: The maximum value for the mean of any subset will be when the subset will only consist of the maximum element from the array. So, in order to count all the possible subsets, find the frequency of the maximum element from the array say cnt and the count of possible subsets will be 2cnt – 1.



Below is the implementation of the above approach:

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
  
// Function to return the coutn of
// subsets with the maximum mean
int cntSubSets(int arr[], int n)
{
  
    // Maximum value from the array
    int maxVal = *max_element(arr, arr + n);
  
    // To store the number of times maximum
    // element appears in the array
    int cnt = 0;
    for (int i = 0; i < n; i++) {
        if (arr[i] == maxVal)
            cnt++;
    }
  
    // Return the count of valid subsets
    return (pow(2, cnt) - 1);
}
  
// Driver code
int main()
{
    int arr[] = { 1, 2, 1, 2 };
    int n = sizeof(arr) / sizeof(int);
  
    cout << cntSubSets(arr, n);
  
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java implementation of the approach
import java.util.*;
  
class GFG 
{
  
// Function to return the coutn of
// subsets with the maximum mean
static int cntSubSets(int arr[], int n)
{
  
    // Maximum value from the array
    int maxVal = Arrays.stream(arr).max().getAsInt();
  
    // To store the number of times maximum
    // element appears in the array
    int cnt = 0;
    for (int i = 0; i < n; i++) 
    {
        if (arr[i] == maxVal)
            cnt++;
    }
  
    // Return the count of valid subsets
    return (int) (Math.pow(2, cnt) - 1);
}
  
// Driver code
public static void main(String []args) 
{
    int arr[] = { 1, 2, 1, 2 };
    int n = arr.length;
  
    System.out.println(cntSubSets(arr, n));
}
}
  
// This code is contributed by Rajput-Ji

chevron_right


Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 implementation of the approach 
  
# Function to return the coutn of 
# subsets with the maximum mean 
def cntSubSets(arr, n) :
  
    # Maximum value from the array 
    maxVal = max(arr); 
  
    # To store the number of times maximum 
    # element appears in the array 
    cnt = 0
    for i in range(n) :
        if (arr[i] == maxVal) :
            cnt += 1
  
    # Return the count of valid subsets 
    return ((2 ** cnt) - 1); 
  
# Driver code 
if __name__ == "__main__" :
      
    arr= [ 1, 2, 1, 2 ];
    n = len(arr);
      
    print(cntSubSets(arr, n)); 
  
# This code is contributed by AnkitRai01

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# implementation of the approach
using System;
using System.Linq;
                      
class GFG 
{
  
// Function to return the coutn of
// subsets with the maximum mean
static int cntSubSets(int []arr, int n)
{
  
    // Maximum value from the array
    int maxVal = arr.Max();
  
    // To store the number of times maximum
    // element appears in the array
    int cnt = 0;
    for (int i = 0; i < n; i++) 
    {
        if (arr[i] == maxVal)
            cnt++;
    }
  
    // Return the count of valid subsets
    return (int) (Math.Pow(2, cnt) - 1);
}
  
// Driver code
public static void Main(String []args) 
{
    int []arr = { 1, 2, 1, 2 };
    int n = arr.Length;
  
    Console.WriteLine(cntSubSets(arr, n));
}
}
  
// This code is contributed by 29AjayKumar

chevron_right


Output:

3

Time Complexity: O(n)

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.




My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.