finding the longest substring of letters in alphabetical order in a given string

Question

When executing my code for the given task, I keep getting the longest string plus the next letter in the iteration. For example, if I use

s = \'azcbobobeggh         


        

Answer 1

You've got a couple items to address. The first is that when you use...

final = result

This is not just assigning the values in result to final. It points the variable 'final' to the memory address containing the list that 'result' is also pointing to. So then if result is changed, so is final. To assign the values in result, use...

final = result[:]

which will give you the values of a slice of the list from beginning to end. Or you can use...

final = list(result)

After that change, you'll need to remove the length comparison in your elif statement.

Edited code:

s = 'azcbobobegghakl'

result = []
final = []

for letters in s:
    result += letters
    if result == sorted(result) and len(result) >= len(final):
        final = list(result)
    elif result != sorted(result):
        result = [result[len(result)-1]]
print "".join(final)