Question

I’m trying to make a function in C that calculates the sum of the elements on the right side of a 2 dimensional square matrix. (only the 1 elements in the below comments)
So far I’ve got this but it’s incorrect since it calculates the sum of the elements for the whole matrix:

  #define N 5
  int a[N][N] ={{0,0,0,0,1},
                {0,0,0,1,1},
                {0,0,1,1,1},
                {0,1,1,1,1},
                {1,1,1,1,1}};


 /*
    {0,0,0,0,1},
    {0,0,0,1,1},
    {0,0,1,1,1},
    {0,1,1,1,1},
    {1,1,1,1,1},
    sum =
                                            a[0][4] + 
                                  a[1][3] + a[1][4] + 
                        a[2][2] + a[2][3] + a[2][4] + 
              a[3][1] + a[3][2] + a[3][3] + a[3][4] +
    a[4][0] + a[4][1] + a[4][2] + a[4][3] + a[4][4]
    */

    int sumSndBisRight(int a[N][N]) {
          int i, j, sum = 0, k = N - 1;
          for( i = 0;i < N;i++) 
              for( j = (N - 1);j >= 0;j--)          
                           sum += a[i][j];          
          return sum;  
    }
    void main() {
    int sum;
    sum = sumSndBisRight(a);
    printf("%d", sum);
    }

Thanks in advance for your help.

Answer 1

Change

for( j = (N - 1);j >= 0;j--)

to

for( j = N-1-i; j < N; j++)