Loop in python for list? Can anybody explain how does this code perform?

Question

A=[1,2,3,4,1]
for n in A:
A[n]=0
print(A)

Result : [0,0,3,0,1]

Answer 1

Add some print statements like this, and run it again, you will see what happens.

The list values change while the code is running.

A=[1,2,3,4,1]
for n in A:
A[n]=0
print(n,A)
print(A)

Answer 2

n is travelling on each value in the list

So when it goes to first value that's 1, it change A[1] that is second element due to 0 based indexing into 0

And therefore when it moves to second value it's already zero due to previous iteration

And it run so on

To understand idexing you can refer :
https://youtube.com/channel/UC3K2nGS4rvTfPlh-Rzx80OA