Pfthb

This is my first post here.

An assignment of my online course in C asked me to remove each row in a real(non dynamically allocated, pointers are not used) whose average sum is greater than the average sum of the whole matrix. The rows should be "removed" by shifting the ones below it up by one position.

I have set up a matrix with the following code:

int matrix[100][100]

Now, my idea was to create a regular 1D array which stores the indexes of the rows to-be-removed.

This is how I did it:

k = 0; 
for (i = 0; i < no_of_rows; i++) 
 average_sum_of_row = 0; 
 for (j = 0; j < no_of_columns; j++) 
 average_sum_of_row += matrix[i][j]; 
 
 average_sum_of_row = average_sum_of_row / no_of_columns;

 if (average_sum_of_row > average_sum_of_matrix) 
 indexes_of_rows_to_remove[k] = i; 
 k++; 
 l++; 
 
 

Which works just fine! I get an array whose elements are the indexes of the rows which need to be removed. However, while implementing my code into the following:

m = 0; 
for (i = 0; i < V; i++) 
 if (indexes_of_rows_to_remove[m] == i) 
 for (k = i; k < no_of_rows - 1; k++) 
 for (j = 0; j < no_of_columns; j++) 
 matrix[k][j] = matrix[k + 1][j]; 
 
 
 i--; 
 no_of_rows--; 
 
 m++; 
 

It does not work. What I used is my existing code of removing a row by shifting the ones below it up and decreasing the number of rows by one, but this simply doesn't work and I don't know why.

I tried using a separate integer(m) to go through all elements of the array of indexes, but for some reason it does not work.

Thanks all!

You can use this algorithm, which skips the rows to be deleted:

k = 0
For i in number of rows:
 If i not to be deleted:
 matrix[k] = matrix[i] # copy the whole row here
 k++

The algorithm you are trying to implement is complicated and very inefficient.