Can this code be modified so that i can find the secondary diagonal elements ?

Question

m=[[1,2,3],[4,5,6],[1,2,3]]
sum=0
for i in range (3):
for j in range (3):
if i==j:
sum=sum+m[i][j]
print(sum)

Answer 1

For a 3×3 matrix, the secondary diagonal is formed by these (i, j) pairs:
(0, 3)
(1, 2)
(2, 1)
(3, 0)

Do you see the relation? As i increases by 1, j decreases by 1. So maybe their sum is fixed? 😉

Let me know if that doesn't make sense.