counting the number of subgrids code example

Example: Counting subgrids

int count_subgrids(const int** color, int n)
{
    int subgrids = 0;
    for(int a=0; a<n; ++a)
        for(int b=a+1; b<n; ++b) {    // loop over pairs (a,b) of rows 
            int count=0;
            for(int i=0; i<n; ++i) {  // loop over all columns
                if(color[a][i]==1 && color[b][i]==1)
                    ++count;
            }
            subgrids += ((count-1)*count)/2;
        }
    return subgrids;
}