Prob3_Solution.py

# 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

# Note: This problem may be 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.

current = ''        
longest = ''
for i in range(len(s)):
 if (s[i] >= s[i-1]):                 # it is like this because in "abc" c > b > a  it should line by its value
  current += s[i]                     # if letter bigger than the one before, it's okay. else: keep [i]
 else:
  current = s[i]
 if len(current) > len(longest):            # if current bigger than 0 :D just put it in longest. 
  longest = current
print("Longest substring in alphabetical order is: " + longest)