Skip to content
Related Articles

Related Articles

Improve Article

Number of elements greater than modified mean in matrix

  • Last Updated : 29 Apr, 2021

Normally mean of the matrix is the average of all elements present in the matrix. Consider a modified mean as the floor of the mean of the row-wise minimum and column-wise maximum. The row-wise minimum is the minimum element from each row of the given matrix and the column-wise maximum is the maximum element from each column. Given a matrix of order n*m, find the number of elements greater than the new mean obtained.

mean = floor ( (sum(row-wise Min) + sum (col-wise Max )) / 
                                  (row_no. + col_no.) )

Examples :  

Input : mat[][] = {1, 5, 6,
                   2, 3, 0,
                   5, 2, 8}
Output : 4

Input : mat[][] = {1, 5,
                   5, 2}
Output : 2

Find the sum of all row-wise minimum and sum of all column-wise maximum. Take the mean of this sum by dividing the sum value with (n+m) i.e., the total number of rows and columns. Now, as we have the mean of the row-wise minimum and column-wise maximum, iterate over the matrix to find the number of elements greater than the calculated mean.
Below is the implementation of the above approach:
 

C++




// CPP program to count number of
// elements greater than mean
#include <bits/stdc++.h>
using namespace std;
 
// define constant for row and column
#define n 4
#define m 5
 
// function to count elements
// greater than mean
int countElements(int mat[][m])
{
    // For each row find minimum
    // element and add to rowSum
    int rowSum = 0;
    for (int i = 0; i < n; i++) {
        int min = mat[i][0];
        for (int j = 1; j < m; j++)
            if (mat[i][j] < min)
                min = mat[i][j];
        rowSum += min;
    }
     
    // For each column find maximum
    // element and add to colSum
    int colSum = 0;
    for (int i = 0; i < m; i++) {
        int max = mat[0][i];
        for (int j = 1; j < n; j++)
            if (max < mat[j][i])
                max = mat[j][i];
        colSum += max;
    }
 
    // Calculate mean of row-wise
    // minimum and column wise maximum
    int mean = (rowSum + colSum) / (m + n);
     
    // For whole matrix count
    // elements greater than mean
    int count = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            if (mean < mat[i][j])
                count++;
    return count;
}
 
// driver function
int main()
{
    int mat[n][m] = { 5, 4, 2, 8, 7,
                      1, 5, 8, 3, 4,
                      8, 5, 4, 6, 0,
                      2, 5, 8, 9, 4 };
    cout << countElements(mat);
    return 0;
}

Java




// Java program to count
// number of elements
// greater than mean
class GFG {
     
    static int n = 4, m = 5;
     
    // function to count
    // elements greater
    // than mean
    static int countElements(int mat[][])
    {
        // For each row find
        // minimum element
        // and add to rowSum
        int rowSum = 0;
        for (int i = 0; i < n; i++)
        {
            int min = mat[i][0];
         
            for (int j = 1; j < m; j++)
                if (mat[i][j] < min)
                    min = mat[i][j];
             
            rowSum += min;
        }
         
        // For each column
        // find maximum
        // element and add
        // to colSum
        int colSum = 0;
        for (int i = 0; i < m; i++) {
            int max = mat[0][i];
         
            for (int j = 1; j < n; j++)
                if (max < mat[j][i])
                    max = mat[j][i];
         
            colSum += max;
        }
     
        // Calculate mean of
        // row-wise minimum
        // and column wise
        // maximum
        int mean = (rowSum + colSum) / (m + n);
         
        // For whole matrix
        // count elements
        // greater than mean
        int count = 0;
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
         
                if (mean < mat[i][j])
                    count++;
         
        return count;
    }
     
    // driver function
    public static void main(String[] args)
    {
        int mat[][] = {{ 5, 4, 2, 8, 7},
                        {1, 5, 8, 3, 4},
                        {8, 5, 4, 6, 0},
                        {2, 5, 8, 9, 4}};
        System.out.println(countElements(mat));
    }
}
 
// This article is contribute by Prerna Saini.

Python3




# Python3 program to count
# number of elements
# greater than mean
n = 4;
m = 5;
 
# Function to count
# elements greater
# than mean
def countElements(mat):
   
    # For each row find
    # minimum element
    # and add to rowSum
    rowSum = 0;
     
    for i in range(n):
        min = mat[i][0];
        for j in range(1, m):
            if (mat[i][j] < min):
                min = mat[i][j];
 
        rowSum += min;
 
    # For each column
    # find maximum
    # element and add
    # to colSum
    colSum = 0;
     
    for i in range(m):
        max = mat[0][i];
        for j in range(1, n):
            if (max < mat[j][i]):
                max = mat[j][i];
 
        colSum += max;
 
    # Calculate mean of
    # row-wise minimum
    # and column wise
    # maximum
    mean = ((rowSum + colSum) /
           (m + n));
 
    # For whole matrix
    # count elements
    # greater than mean
    count = 0;
    for i in range(n):
        for j in range(m):
            if (mean < mat[i][j]):
                count += 1;
 
    return count;
 
# Driver code
if __name__ == '__main__':
   
    mat = [[5, 4, 2, 8, 7],
           [1, 5, 8, 3, 4],
           [8, 5, 4, 6, 0],
           [2, 5, 8, 9, 4]];
    print(countElements(mat));
 
# This code is contributed by 29AjayKumar

C#




// C# program to count number of
// elements greater than mean
using System;
 
class GFG {
     
    static int n = 4, m = 5;
     
    // function to count elements
    // greater than mean
    static int countElements(int [,]mat)
    {
        // For each row find minimum
        // element and add to rowSum
        int rowSum = 0;
        for (int i = 0; i < n; i++)
        {
            int min = mat[i,0];
         
            for (int j = 1; j < m; j++)
                if (mat[i,j] < min)
                    min = mat[i,j];
             
            rowSum += min;
        }
         
        // For each column find maximum
        // element and add to colSum
        int colSum = 0;
        for (int i = 0; i < m; i++) {
            int max = mat[0,i];
         
            for (int j = 1; j < n; j++)
                if (max < mat[j,i])
                    max = mat[j,i];
         
            colSum += max;
        }
     
        // Calculate mean of row-wise minimum
        // and column wise maximum
        int mean = (rowSum + colSum) / (m + n);
         
        // For whole matrix count
        // elements greater than mean
        int count = 0;
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
         
                if (mean < mat[i,j])
                    count++;
         
        return count;
    }
     
    // Driver function
    public static void Main()
    {
        int [,]mat = {{5, 4, 2, 8, 7},
                      {1, 5, 8, 3, 4},
                      {8, 5, 4, 6, 0},
                      {2, 5, 8, 9, 4}};
    Console.Write(countElements(mat));
    }
}
 
// This article is contribute by nitin mittal.

PHP




<?php
// PHP program to count number of
// elements greater than mean
 
// define constant for
// row and column
$n = 4;
$m = 5;
 
// function to count elements
// greater than mean
function countElements($mat)
{
     
    // For each row find minimum
    // element and add to rowSum
    $rowSum = 0;
    global $n, $m;
    for ($i = 0; $i < $n; $i++)
    {
        $min = $mat[$i][0];
        for ($j = 1; $j < $m; $j++)
            if ($mat[$i][$j] < $min)
                $min = $mat[$i][$j];
        $rowSum += $min;
    }
     
    // For each column find maximum
    // element and add to colSum
    $colSum = 0;
    for ($i = 0; $i < $m; $i++)
    {
        $max = $mat[0][$i];
        for ($j = 1; $j < $n; $j++)
            if ($max < $mat[$j][$i])
                $max = $mat[$j][$i];
        $colSum += $max;
    }
 
    // Calculate mean of row-wise
    // minimum and column wise maximum
    $mean = ($rowSum + $colSum) / ($m + $n);
     
    // For whole matrix count
    // elements greater than mean
    $count = 0;
    for ($i = 0; $i < $n; $i++)
        for ($j = 0; $j < $m; $j++)
            if ($mean < $mat[$i][$j])
                $count++;
    return $count;
}
 
// Driver Code
$mat = array(array(5, 4, 2, 8, 7),
             array(1, 5, 8, 3, 4),
             array(8, 5, 4, 6, 0),
             array(2, 5, 8, 9, 4));
echo countElements($mat);
// This code is contribute by vt_m.
?>

Javascript




<script>
 
// Javascript program to count number of
// elements greater than mean
 
// define constant for row and column
var n = 4
var m = 5
 
// function to count elements
// greater than mean
function countElements(mat)
{
    // For each row find minimum
    // element and add to rowSum
    var rowSum = 0;
    for (var i = 0; i < n; i++) {
        var min = mat[i][0];
        for (var j = 1; j < m; j++)
            if (mat[i][j] < min)
                min = mat[i][j];
        rowSum += min;
    }
     
    // For each column find maximum
    // element and add to colSum
    var colSum = 0;
    for (var i = 0; i < m; i++) {
        var max = mat[0][i];
        for (var j = 1; j < n; j++)
            if (max < mat[j][i])
                max = mat[j][i];
        colSum += max;
    }
 
    // Calculate mean of row-wise
    // minimum and column wise maximum
    var mean = (rowSum + colSum) / (m + n);
     
    // For whole matrix count
    // elements greater than mean
    var count = 0;
    for (var i = 0; i < n; i++)
        for (var j = 0; j < m; j++)
            if (mean < mat[i][j])
                count++;
    return count;
}
 
// driver function
var mat = [ [5, 4, 2, 8, 7],
                  [1, 5, 8, 3, 4],
                  [8, 5, 4, 6, 0],
                  [2, 5, 8, 9, 4 ]];
document.write( countElements(mat));
 
</script>

Output:  

11

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.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.




My Personal Notes arrow_drop_up
Recommended Articles
Page :