Number of elements greater than modified mean in matrix

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

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Find 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., total number of rows and columns. Now, as we have the mean of row-wise minimum and column-wise maximum, iterate over the matrix to find the number of elements greater than calculated mean.

Below is the implementation of above approach:

C++

 // CPP program to count number of // elements greater than mean #include 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];         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[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];                        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[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.

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



Output:

11

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