edx python intro pset 1 problem 3

#!/usr/bin/env python3

#Alphabetical substrings problem 3 Problem Set 1 EDX 6.00.1x Introduction to Computer Science and Programming Using Python Python 3.5 August 2016

"""
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.
"""




import string
import random

randstr = lambda x: ''.join(random.choice(string.ascii_lowercase) for _ in range(x))

def ugly(s):
    #also wrong
    pos = 0
    l = []
    ss = []
    while pos <= (len(s)-1):
        if pos == (len(s)-1):
            if len(ss) == 0:
                pass
            elif s[pos] > ss[-1]:
                ss.append(s[pos])
            l.append(ss)
            break
        elif s[pos] <= s[pos+1]:
            ss.append(s[pos])
            pos += 1
        else:
            ss.append(s[pos])
            pos +=1
            l.append(ss)
            ss = []
    return l



def better(s):
    res_list = []
    res = []
    for x,y in zip (s,s[1:]):
        if res == []:
            res.append(x)
        if x<=y:
            res.append(y)
        else:
            res_list.append(res)
            res = []
    res_list.append(res)
    return res_list

 
def worse(s):
    for x,y in zip(s,s[1:]):
        if x<=y:
            yield x
        else:
            yield x+';'

lworse = lambda s: ''.join(worse(s)).split(sep=';')

def mad(s):                      
    res = s[0]
    lres = ''
    for char in s[1:]:
        if char >= res[-1]:
            res += char
        else:
            if len(res) > len(lres):
                lres = res
            res = char       
    return max(lres,res,key=len)


##
res = s[0]
lres = ''
for char in s[1:]:
    if char >= res[-1]:
        res += char
    else:
        if len(res) > len(lres):
            lres = res
        res = char
print('Longest substring in alphabetical order is: ', max(lres,res,key=len))
##

def good(s):
    res = s[0]
    lres = ''
    counter=1
    lcounter=0
    for char in s[1:]:
        if char >= res[-1]:
            res += char
            counter +=1
        else:
            if counter > lcounter:
                lres = res
                lcounter = counter
            counter = 1
            res = char       
    return max(lres,res,key=len)

oneliner = lambda s: max(''.join(x if x<=y else x+';' for x,y in zip(s,s[1:])).split(sep=';'),key=len)


s = randstr(9999)

ugly(s)
better(s)
worse(s)

print ('Longest substring in alphabetical order is: ', ''.join(max(lworse(s), key=len)))