How does it work ?

Question

f = 1
A = [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
for i in range(0, 3):
f =f*i
for j in range(0, 3):
A[i][j] = f
print(A)

Answer 1

You can index arrays by [], each position is numbered from 0 to length-1. If you store arrays in arrays, you can do it for the inner lists too. So A[0][2] is 3 (first element of outer array, and there the third element).

The embedded for loops create the indexes for the 2d array: two numbers i and j from 0 to 2.

And then A[i][j] will be changed to what f is now.

You only have to play this out in your mind or on paper step by step.

The interesting point is line 4. Let's do this for i == 0:

f = 1*0 -> f == 0, right?

So from now on, whatever i will be, f will remain 0 (0*1, 0*2).

And if f is always 0, then every spot of the array will be set to 0 in line 6.

Answer 2

the answer is likely to be?

Answer 3

Have you read my post?