Quiz1
How do you reverse an array without additional space?
Answer1
You can use the built-in list.reverse method.
https://docs.python.org/3/library/stdtypes.html#sequence.reverse
Reverse the items of the sequence in place. This method maintains economy of space when reversing a large sequence.
So you can reverse in place without additional space.
arr = [1, 2, 3]
arr.reverse()
print(arr) # [3, 2, 1]
Quiz2
What if you cannot use list.reverse?
Answer2
We can do it like this.
l, r = 0, len(arr) - 1
while l < r:
arr[l], arr[r] = arr[r], arr[l]
l += 1
r -= 1