Python help!

Question

Hi, I can’t understand why the answer to this is 5?

Thank you!

a = [x for x in range(4)]
print(sum(a[2::-2] + a[::-3]))

Answer 1

First you have : a == [0,1,2,3]
and a[2::-2] == [2,0] # -2 is the step in this case.
and you have also : a[::-3] == [3,0]
so a[2::-2]+a[::-3]==[2,0,3,0]
and the sum is 5

#for more precision
a[::-3] == [a[-1] , a[-4]]
a[2::-2] == [a[2] , a[0]]
a[::] == a

Answer 2

YoPycode Thank you!

Answer 3

K Kana You are welcome! Good luck 👍