Switch indexes, create the next highest number using the same exact 9 digits presented

Question

So I received a challenge that states the following: \"Design a program that takes as input a 9 digit number where no digit appears twice and produces as output an arrangeme

Answer 1

input[8] == input[7]
input[7] == temp

you probably meant:

input[8] = input[7]
input[7] = temp

didn't you?

Which, as stated in the comments, wouldn't work directly on the string, as it is immutable in Python. So, as a first step, you could make a list of characters from that string:

input = list(input)

and as a last step, get a string back from the modified list:

input = ''.join(input)

BTW, you might want to benefit from Python tuple unpacking which allows you to swap two variables without having to introduce a third one:

input[7], input[8] = input[8], input[7]