[0] [1] [2] [3]
[0]  1   1   0   0 
[1]  1   1   1   0
[2]  0   1   1   1
[3]  0   0   1   1

[0] = a[0][0]
[1] = a[0][1]
[2] = a[1][0]
[3] = a[1][1]
[4] = a[1][2]
[5] = a[2][1]
[6] = a[2][2]
[7] = a[2][3]
[8] = a[3][2]
[9] = a[3][3]

if (row == 0)
   b[i] = column
else {
   i = 2;

   for (j = 1; j < row; j++)
       i+= j;
    if (column == row) i++;
    if (column == row+1) i+= 2;