Question

Assume s is a string of lower case characters.

Write a program that prints the longest substring of s in which the letters occur in alphabetical order. For example, if s = 'azcbobobegghakl', then your program should print

Longest substring in alphabetical order is: beggh
In the case of ties, print the first substring. For example, if s = 'abcbcd', then your program should print

Longest substring in alphabetical order is: abc
For problems such as these, do not include raw_input statements or define the variable s in any way. Our automating testing will provide a value of s for you - so the code you submit in the following box should assume s is already defined. If you are confused by this instruction, please review L2 Problems 10 and 11 before you begin this problem set.

Note: This problem is fairly challenging. We encourage you to work smart. If you've spent more than a few hours on this problem, we suggest that you move on to a different part of the course. If you have time, come back to this problem after you've had a break and cleared your head.

Answer 1

DO IT BY YOURSELF OR YOU WILL NOT LEARN! GOOD LUCK!

Answer 2

def test():
index = 1
prev_index = 0
count = 0
global largest
largest = ''
test = s[prev_index]

while count < len(s):
if ord(s[index]) > ord(s[prev_index]):
test += s[index]
index += 1
prev_index += 1
elif ord(s[index]) == ord(s[prev_index]):
test += s[index]
index += 1
prev_index += 1
else:
if len(largest) < len(test):
largest = test[:]
test = s[index]
prev_index += 1
index += 1
count += 1
return largest
try:
test()
except IndexError:
pass
finally:
print largest