Question

Given a 2-D array A[-20 .... 10, 8 ..... 16] where the starting location is 20. Consider that the memory space occupied by the array is 4 bytes and stored is row-major order. What is the location of A[4][16]?

• A. 920
• B. 820
• C. 630
• D. 720

Answer 1

The correct option is B 820

Given : range : [-20 .... 10][8 ..... 16]
location : A[4][16]
No. of rows (m) = 10 - (-20) + 1 = 31
No. of columns (n) = 15 - 8 + 1 = 8
New range : [0 ... 30][0 .... 7]
New location : A[4 - (-20)][16 - 8]
of A[4][16]
$\Rightarrow$ A[24][8]
A[0][0] = 20

Row major order
A[i][j] = B.A. + [j + i$\times$ n] $\times$ memory
we know B.A. = 20
A[24][8] = 20 + [8 + 24 $\times$ 8] $\times$ 4
= 20 + [8 + 192] $\times$ 4
= 20 + 200 $\times$ 4
A[24][8] = 820.