Develop Reference

How do I get the shortest repitition of something in an array?

Let's say you have a list which only has two types of values and goes something like ['t','r','r','r','t','t','r','r','t'] and you want to find the length of the smallest sequence number of 'r's which have 't's at both ends.
In this case the smallest sequence of 'r' has a length of 2, because there is first t,r,r,r,t and then t,r,r,t, and the latter has the smallest number of 'r's in a row surrounded by 't' and the number of 'r's is 2.
How would I code for finding that number?
This is from a problem of trying of going to a play with your friend, and you want to sit as close as possible with your friend, so you are trying to find the smallest amount of taken seats in between two free seats at a play. "#" is a taken seat and a "." is a free seat. you are given the amount of seats, and the seating arrangement (free seats and taken seats), and they are all in one line.
An example of an input is:
5
#.##.
where there are two taken seats(##) in between two free seats.
Here is my code which is not working for inputs that I don't know, but working for inputs I throw at it.
import sys
seats = int(input())
configuration = input()
seatsArray = []
betweenSeats = 1
betweenSeatsMin = 1
checked = 0
theArray = []
dotCount = 0
for i in configuration:
seatsArray.append(i)
for i in range(len(seatsArray)):
if i == len(seatsArray) - 1:
break
if seatsArray[i] == "." and seatsArray[i+1] == ".":
print(0)
sys.exit()
for i in range(0,len(seatsArray)):
if i > 0:
if checked == seats:
break
checked += 1
if seatsArray[i] == "#":
if i > 0:
if seatsArray[i-1] == "#":
betweenSeats += 1
if seatsArray[i] == ".":
dotCount += 1
if dotCount > 1:
theArray.append(betweenSeats)
betweenSeats = 1
theArray = sorted(theArray)
if theArray.count(1) > 0:
theArray.remove(1)
theArray = list(dict.fromkeys(theArray))
print(theArray[0])

This is a noob and a !optimal approach to your problem using a counter for the minimum and maximum sequence where ew compare both and return the minimum.
''' create a funciton that
will find min sequence
of target char
in a list'''
def finder(a, target):
max_counter = 0
min_counter = 0
''' iterate through our list
and if the element is the target
increase our max counter by 1
'''
for i in x:
if i == target:
max_counter += 1
'''min here is 0
so it will always be less
so we overwrite it's value
with the value of max_counter'''
if min_counter < max_counter:
min_counter = max_counter
'''at last iteration max counter will be less than min counter
so we overwrite it'''
if max_counter < min_counter:
min_counter = max_counter
else:
max_counter = 0
return min_counter
x = ['t','r','r','r','t','t','r','r','t','t','t','r','t']
y = 'r'
print(finder(x,y))

Create a string from list and then search for pattern required and then count r in the found matches and then take min of it
Code:
import re
lst = ['t','r','r','r','t','t','r','r','t']
text = ''.join(lst)
pattern = '(?<=t)r+(?=t)'
smallest_r_seq = min(match.group().count('r') for match in re.finditer(pattern, text))
print(smallest_r_seq)
Output:
2

Python: How to find all ways to decode a string?

I'm trying to solve this problem but it fails with input "226".
Problem:
A message containing letters from A-Z is being encoded to numbers using the following mapping:
'A' -> 1
'B' -> 2
...
'Z' -> 26
Given a non-empty string containing only digits, determine the total number of ways to decode it.
My Code:
class Solution:
def numDecodings(self, s: str) -> int:
decode =[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]
ways = []
for d in decode:
for i in s:
if str(d) == s or str(d) in s:
ways.append(d)
if int(i) in decode:
ways.append(str(i))
return len(ways)
My code returns 2. It only takes care of combinations (22,6) and (2,26).
It should be returning 3, so I'm not sure how to take care of the (2,2,6) combination.

Looks like this problem can be broken down into many subproblems thus can be solved recursively
Subproblem 1 = when the last digit of the string is valid ( i.e. non zero number ) for that you can just recur for (n-1) digits left
if s[n-1] > "0":
count = number_of_decodings(s,n-1)
Subproblem 2 = when last 2 digits form a valid number ( less then 27 ) for that you can just recur for remaining (n-2) digits
if (s[n - 2] == '1' or (s[n - 2] == '2' and s[n - 1] < '7') ) :
count += number_of_decodings(s, n - 2)
Base Case = length of the string is 0 or 1
if n == 0 or n == 1 :
return 1
EDIT: A quick searching on internet , I found another ( more interesting ) method to solve this particular problem which uses dynamic programming to solve this problem
# A Dynamic Programming based function
# to count decodings
def countDecodingDP(digits, n):
count = [0] * (n + 1); # A table to store
# results of subproblems
count[0] = 1;
count[1] = 1;
for i in range(2, n + 1):
count[i] = 0;
# If the last digit is not 0, then last
# digit must add to the number of words
if (digits[i - 1] > '0'):
count[i] = count[i - 1];
# If second last digit is smaller than 2
# and last digit is smaller than 7, then
# last two digits form a valid character
if (digits[i - 2] == '1' or
(digits[i - 2] == '2' and
digits[i - 1] < '7') ):
count[i] += count[i - 2];
return count[n];
the above solution solves the problem in complexity of O(n) and uses the similar method as that of fibonacci number problem
source: https://www.geeksforgeeks.org/count-possible-decodings-given-digit-sequence/

This seemed like a natural for recursion. Since I was bored, and the first answer didn't use recursion and didn't return the actual decodings, I thought there was room for improvement. For what it's worth...
def encodings(str, prefix = ''):
encs = []
if len(str) > 0:
es = encodings(str[1:], (prefix + ',' if prefix else '') + str[0])
encs.extend(es)
if len(str) > 1 and int(str[0:2]) <= 26:
es = encodings(str[2:], (prefix + ',' if prefix else '') + str[0:2])
encs.extend(es)
return encs if len(str) else [prefix]
This returns a list of the possible decodings. To get the count, you just take the length of the list. Here a sample run:
encs = encodings("123")
print("{} {}".format(len(encs), encs))
with result:
3 ['1,2,3', '1,23', '12,3']
Another sample run:
encs = encodings("123123")
print("{} {}".format(len(encs), encs))
with result:
9 ['1,2,3,1,2,3', '1,2,3,1,23', '1,2,3,12,3', '1,23,1,2,3', '1,23,1,23', '1,23,12,3', '12,3,1,2,3', '12,3,1,23', '12,3,12,3']

How to optimize an O(N*M) to be O(n**2)?

I am trying to solve USACO's Milking Cows problem. The problem statement is here: https://train.usaco.org/usacoprob2?S=milk2&a=n3lMlotUxJ1
Given a series of intervals in the form of a 2d array, I have to find the longest interval and the longest interval in which no milking was occurring.
Ex. Given the array [[500,1200],[200,900],[100,1200]], the longest interval would be 1100 as there is continuous milking and the longest interval without milking would be 0 as there are no rest periods.
I have tried looking at whether utilizing a dictionary would decrease run times but I haven't had much success.
f = open('milk2.in', 'r')
w = open('milk2.out', 'w')
#getting the input
farmers = int(f.readline().strip())
schedule = []
for i in range(farmers):
schedule.append(f.readline().strip().split())
#schedule = data
minvalue = 0
maxvalue = 0
#getting the minimums and maximums of the data
for time in range(farmers):
schedule[time][0] = int(schedule[time][0])
schedule[time][1] = int(schedule[time][1])
if (minvalue == 0):
minvalue = schedule[time][0]
if (maxvalue == 0):
maxvalue = schedule[time][1]
minvalue = min(schedule[time][0], minvalue)
maxvalue = max(schedule[time][1], maxvalue)
filled_thistime = 0
filled_max = 0
empty_max = 0
empty_thistime = 0
#goes through all the possible items in between the minimum and the maximum
for point in range(minvalue, maxvalue):
isfilled = False
#goes through all the data for each point value in order to find the best values
for check in range(farmers):
if point >= schedule[check][0] and point < schedule[check][1]:
filled_thistime += 1
empty_thistime = 0
isfilled = True
break
if isfilled == False:
filled_thistime = 0
empty_thistime += 1
if (filled_max < filled_thistime) :
filled_max = filled_thistime
if (empty_max < empty_thistime) :
empty_max = empty_thistime
print(filled_max)
print(empty_max)
if (filled_max < filled_thistime):
filled_max = filled_thistime
w.write(str(filled_max) + " " + str(empty_max) + "\n")
f.close()
w.close()
The program works fine, but I need to decrease the time it takes to run.

A less pretty but more efficient approach would be to solve this like a free list, though it is a bit more tricky since the ranges can overlap. This method only requires looping through the input list a single time.
def insert(start, end):
for existing in times:
existing_start, existing_end = existing
# New time is a subset of existing time
if start >= existing_start and end <= existing_end:
return
# New time ends during existing time
elif end >= existing_start and end <= existing_end:
times.remove(existing)
return insert(start, existing_end)
# New time starts during existing time
elif start >= existing_start and start <= existing_end:
# existing[1] = max(existing_end, end)
times.remove(existing)
return insert(existing_start, end)
# New time is superset of existing time
elif start <= existing_start and end >= existing_end:
times.remove(existing)
return insert(start, end)
times.append([start, end])
data = [
[500,1200],
[200,900],
[100,1200]
]
times = [data[0]]
for start, end in data[1:]:
insert(start, end)
longest_milk = 0
longest_gap = 0
for i, time in enumerate(times):
duration = time[1] - time[0]
if duration > longest_milk:
longest_milk = duration
if i != len(times) - 1 and times[i+1][0] - times[i][1] > longest_gap:
longes_gap = times[i+1][0] - times[i][1]
print(longest_milk, longest_gap)

As stated in the comments, if the input is sorted, the complexity could be O(n), if that's not the case we need to sort it first and the complexity is O(nlog n):
lst = [ [300,1000],
[700,1200],
[1500,2100] ]
from itertools import groupby
longest_milking = 0
longest_idle = 0
l = sorted(lst, key=lambda k: k[0])
for v, g in groupby(zip(l[::1], l[1::1]), lambda k: k[1][0] <= k[0][1]):
l = [*g][0]
if v:
mn, mx = min(i[0] for i in l), max(i[1] for i in l)
if mx-mn > longest_milking:
longest_milking = mx-mn
else:
mx = max((i2[0] - i1[1] for i1, i2 in zip(l[::1], l[1::1])))
if mx > longest_idle:
longest_idle = mx
# corner case, N=1 (only one interval)
if len(lst) == 1:
longest_milking = lst[0][1] - lst[0][0]
print(longest_milking)
print(longest_idle)
Prints:
900
300
For input:
lst = [ [500,1200],
[200,900],
[100,1200] ]
Prints:
1100
0

Without using built-in functions, a function should reverse a string without changing the '$' position

I need a Python function which gives reversed string with the following conditions.
$ position should not change in the reversed string.
Should not use Python built-in functions.
Function should be an efficient one.
Example : 'pytho$n'
Result : 'nohty$p'
I have already tried with this code:
list = "$asdasdas"
list1 = []
position = ''
for index, i in enumerate(list):
if i == '$':
position = index
elif i != '$':
list1.append(i)
reverse = []
for index, j in enumerate( list1[::-1] ):
if index == position:
reverse.append( '$' )
reverse.append(j)
print reverse
Thanks in advance.

Recognise that it's a variation on the partitioning step of the Quicksort algorithm, using two pointers (array indices) thus:
data = list("foo$barbaz$$")
i, j = 0, len(data) - 1
while i < j:
while i < j and data[i] == "$": i += 1
while i < j and data[j] == "$": j -= 1
data[i], data[j] = data[j], data[i]
i, j = i + 1, j - 1
"".join(data)
'zab$raboof$$'
P.S. it's a travesty to write this in Python!
A Pythonic solution could look like this:
def merge(template, data):
for c in template:
yield c if c == "$" else next(data)
data = "foo$barbaz$$"
"".join(merge(data, reversed([c for c in data if c != "$"])))
'zab$raboof$$'

Wrote this without using any inbuilt functions. Hope it fulfils your criteria -
string = "zytho$n"
def reverse(string):
string_new = string[::-1]
i = 0
position = 0
position_new = 0
for char in string:
if char=="$":
position = i
break
else:
i = i + 1
j = 0
for char in string_new:
if char=="$":
position_new = i
break
else:
j = j + 1
final_string = string_new[:position_new]+string_new[position_new+1:position+1]+"$"+string_new[position+1:]
return(final_string)
string_new = reverse(string)
print(string_new)
The output of this is-
nohty$x
To explain the code to you, first I used [::-1], which is just taking the last position of the string and moving forward so as to reverse the string. Then I found the position of the $ in both the new and the old string. I found the position in the form of an array, in case you have more than one $ present. However, I took for granted that you have just one $ present, and so took the [0] index of the array. Next I stitched back the string using four things - The part of the new string upto the $ sign, the part of the new string from after the dollar sign to the position of the $ sign in the old string, then the $ sign and after that the rest of the new string.

Finding longest substring in alphabetical order

EDIT: I am aware that a question with similar task was already asked in SO but I'm interested to find out the problem in this specific piece of code. I am also aware that this problem can be solved without using recursion.
The task is to write a program which will find (and print) the longest sub-string in which the letters occur in alphabetical order. If more than 1 equally long sequences were found, then the first one should be printed. For example, the output for a string abczabcd will be abcz.
I have solved this problem with recursion which seemed to pass my manual tests. However when I run an automated tests set which generate random strings, I have noticed that in some cases, the output is incorrect. For example:
if s = 'hixwluvyhzzzdgd', the output is hix instead of luvy
if s = 'eseoojlsuai', the output is eoo instead of jlsu
if s = 'drurotsxjehlwfwgygygxz', the output is dru instead of ehlw
After some time struggling, I couldn't figure out what is so special about these strings that causes the bug.
This is my code:
pos = 0
maxLen = 0
startPos = 0
endPos = 0
def last_pos(pos):
if pos < (len(s) - 1):
if s[pos + 1] >= s[pos]:
pos += 1
if pos == len(s)-1:
return len(s)
else:
return last_pos(pos)
return pos
for i in range(len(s)):
if last_pos(i+1) != None:
diff = last_pos(i) - i
if diff - 1 > maxLen:
maxLen = diff
startPos = i
endPos = startPos + diff
print s[startPos:endPos+1]

There are many things to improve in your code but making minimum changes so as to make it work. The problem is you should have if last_pos(i) != None: in your for loop (i instead of i+1) and you should compare diff (not diff - 1) against maxLen. Please read other answers to learn how to do it better.
for i in range(len(s)):
if last_pos(i) != None:
diff = last_pos(i) - i + 1
if diff > maxLen:
maxLen = diff
startPos = i
endPos = startPos + diff - 1

Here. This does what you want. One pass, no need for recursion.
def find_longest_substring_in_alphabetical_order(s):
groups = []
cur_longest = ''
prev_char = ''
for c in s.lower():
if prev_char and c < prev_char:
groups.append(cur_longest)
cur_longest = c
else:
cur_longest += c
prev_char = c
return max(groups, key=len) if groups else s
Using it:
>>> find_longest_substring_in_alphabetical_order('hixwluvyhzzzdgd')
'luvy'
>>> find_longest_substring_in_alphabetical_order('eseoojlsuai')
'jlsu'
>>> find_longest_substring_in_alphabetical_order('drurotsxjehlwfwgygygxz')
'ehlw'
Note: It will probably break on strange characters, has only been tested with the inputs you suggested. Since this is a "homework" question, I will leave you with the solution as is, though there is still some optimization to be done, I wanted to leave it a little bit understandable.

You can use nested for loops, slicing and sorted. If the string is not all lower-case then you can convert the sub-strings to lower-case before comparing using str.lower:
def solve(strs):
maxx = ''
for i in xrange(len(strs)):
for j in xrange(i+1, len(strs)):
s = strs[i:j+1]
if ''.join(sorted(s)) == s:
maxx = max(maxx, s, key=len)
else:
break
return maxx
Output:
>>> solve('hixwluvyhzzzdgd')
'luvy'
>>> solve('eseoojlsuai')
'jlsu'
>>> solve('drurotsxjehlwfwgygygxz')
'ehlw'

Python has a powerful builtin package itertools and a wonderful function within groupby
An intuitive use of the Key function can give immense mileage.
In this particular case, you just have to keep a track of order change and group the sequence accordingly. The only exception is the boundary case which you have to handle separately
Code
def find_long_cons_sub(s):
class Key(object):
'''
The Key function returns
1: For Increasing Sequence
0: For Decreasing Sequence
'''
def __init__(self):
self.last_char = None
def __call__(self, char):
resp = True
if self.last_char:
resp = self.last_char < char
self.last_char = char
return resp
def find_substring(groups):
'''
The Boundary Case is when an increasing sequence
starts just after the Decresing Sequence. This causes
the first character to be in the previous group.
If you do not want to handle the Boundary Case
seperately, you have to mak the Key function a bit
complicated to flag the start of increasing sequence'''
yield next(groups)
try:
while True:
yield next(groups)[-1:] + next(groups)
except StopIteration:
pass
groups = (list(g) for k, g in groupby(s, key = Key()) if k)
#Just determine the maximum sequence based on length
return ''.join(max(find_substring(groups), key = len))
Result
>>> find_long_cons_sub('drurotsxjehlwfwgygygxz')
'ehlw'
>>> find_long_cons_sub('eseoojlsuai')
'jlsu'
>>> find_long_cons_sub('hixwluvyhzzzdgd')
'luvy'

Simple and easy.
Code :
s = 'hixwluvyhzzzdgd'
r,p,t = '','',''
for c in s:
if p <= c:
t += c
p = c
else:
if len(t) > len(r):
r = t
t,p = c,c
if len(t) > len(r):
r = t
print 'Longest substring in alphabetical order is: ' + r
Output :
Longest substring in alphabetical order which appeared first: luvy

Here is a single pass solution with a fast loop. It reads each character only once. Inside the loop operations are limited to
1 string comparison (1 char x 1 char)
1 integer increment
2 integer subtractions
1 integer comparison
1 to 3 integer assignments
1 string assignment
No containers are used. No function calls are made. The empty string is handled without special-case code. All character codes, including chr(0), are properly handled. If there is a tie for the longest alphabetical substring, the function returns the first winning substring it encountered. Case is ignored for purposes of alphabetization, but case is preserved in the output substring.
def longest_alphabetical_substring(string):
start, end = 0, 0 # range of current alphabetical string
START, END = 0, 0 # range of longest alphabetical string yet found
prev = chr(0) # previous character
for char in string.lower(): # scan string ignoring case
if char < prev: # is character out of alphabetical order?
start = end # if so, start a new substring
end += 1 # either way, increment substring length
if end - start > END - START: # found new longest?
START, END = start, end # if so, update longest
prev = char # remember previous character
return string[START : END] # return longest alphabetical substring
Result
>>> longest_alphabetical_substring('drurotsxjehlwfwgygygxz')
'ehlw'
>>> longest_alphabetical_substring('eseoojlsuai')
'jlsu'
>>> longest_alphabetical_substring('hixwluvyhzzzdgd')
'luvy'
>>>

a lot more looping, but it gets the job done
s = raw_input("Enter string")
fin=""
s_pos =0
while s_pos < len(s):
n=1
lng=" "
for c in s[s_pos:]:
if c >= lng[n-1]:
lng+=c
n+=1
else :
break
if len(lng) > len(fin):
fin= lng`enter code here`
s_pos+=1
print "Longest string: " + fin

def find_longest_order():
`enter code here`arr = []
`enter code here`now_long = ''
prev_char = ''
for char in s.lower():
if prev_char and char < prev_char:
arr.append(now_long)
now_long = char
else:
now_long += char
prev_char = char
if len(now_long) == len(s):
return now_long
else:
return max(arr, key=len)
def main():
print 'Longest substring in alphabetical order is: ' + find_longest_order()
main()

Simple and easy to understand:
s = "abcbcd" #The original string
l = len(s) #The length of the original string
maxlenstr = s[0] #maximum length sub-string, taking the first letter of original string as value.
curlenstr = s[0] #current length sub-string, taking the first letter of original string as value.
for i in range(1,l): #in range, the l is not counted.
if s[i] >= s[i-1]: #If current letter is greater or equal to previous letter,
curlenstr += s[i] #add the current letter to current length sub-string
else:
curlenstr = s[i] #otherwise, take the current letter as current length sub-string
if len(curlenstr) > len(maxlenstr): #if current cub-string's length is greater than max one,
maxlenstr = curlenstr; #take current one as max one.
print("Longest substring in alphabetical order is:", maxlenstr)

s = input("insert some string: ")
start = 0
end = 0
temp = ""
while end+1 <len(s):
while end+1 <len(s) and s[end+1] >= s[end]:
end += 1
if len(s[start:end+1]) > len(temp):
temp = s[start:end+1]
end +=1
start = end
print("longest ordered part is: "+temp)

I suppose this is problem set question for CS6.00.1x on EDX. Here is what I came up with.
s = raw_input("Enter the string: ")
longest_sub = ""
last_longest = ""
for i in range(len(s)):
if len(last_longest) > 0:
if last_longest[-1] <= s[i]:
last_longest += s[i]
else:
last_longest = s[i]
else:
last_longest = s[i]
if len(last_longest) > len(longest_sub):
longest_sub = last_longest
print(longest_sub)

I came up with this solution
def longest_sorted_string(s):
max_string = ''
for i in range(len(s)):
for j in range(i+1, len(s)+1):
string = s[i:j]
arr = list(string)
if sorted(string) == arr and len(max_string) < len(string):
max_string = string
return max_string

Assuming this is from Edx course:
till this question, we haven't taught anything about strings and their advanced operations in python
So, I would simply go through the looping and conditional statements
string ="" #taking a plain string to represent the then generated string
present ="" #the present/current longest string
for i in range(len(s)): #not len(s)-1 because that totally skips last value
j = i+1
if j>= len(s):
j=i #using s[i+1] simply throws an error of not having index
if s[i] <= s[j]: #comparing the now and next value
string += s[i] #concatinating string if above condition is satisied
elif len(string) != 0 and s[i] > s[j]: #don't want to lose the last value
string += s[i] #now since s[i] > s[j] #last one will be printed
if len(string) > len(present): #1 > 0 so from there we get to store many values
present = string #swapping to largest string
string = ""
if len(string) > len(present): #to swap from if statement
present = string
if present == s[len(s)-1]: #if no alphabet is in order then first one is to be the output
present = s[0]
print('Longest substring in alphabetical order is:' + present)

I agree with #Abhijit about the power of itertools.groupby() but I took a simpler approach to (ab)using it and avoided the boundary case problems:
from itertools import groupby
LENGTH, LETTERS = 0, 1
def longest_sorted(string):
longest_length, longest_letters = 0, []
key, previous_letter = 0, chr(0)
def keyfunc(letter):
nonlocal key, previous_letter
if letter < previous_letter:
key += 1
previous_letter = letter
return key
for _, group in groupby(string, keyfunc):
letters = list(group)
length = len(letters)
if length > longest_length:
longest_length, longest_letters = length, letters
return ''.join(longest_letters)
print(longest_sorted('hixwluvyhzzzdgd'))
print(longest_sorted('eseoojlsuai'))
print(longest_sorted('drurotsxjehlwfwgygygxz'))
print(longest_sorted('abcdefghijklmnopqrstuvwxyz'))
OUTPUT
> python3 test.py
luvy
jlsu
ehlw
abcdefghijklmnopqrstuvwxyz
>

s = 'azcbobobegghakl'
i=1
subs=s[0]
subs2=s[0]
while(i<len(s)):
j=i
while(j<len(s)):
if(s[j]>=s[j-1]):
subs+=s[j]
j+=1
else:
subs=subs.replace(subs[:len(subs)],s[i])
break
if(len(subs)>len(subs2)):
subs2=subs2.replace(subs2[:len(subs2)], subs[:len(subs)])
subs=subs.replace(subs[:len(subs)],s[i])
i+=1
print("Longest substring in alphabetical order is:",subs2)

s = 'gkuencgybsbezzilbfg'
x = s.lower()
y = ''
z = [] #creating an empty listing which will get filled
for i in range(0,len(x)):
if i == len(x)-1:
y = y + str(x[i])
z.append(y)
break
a = x[i] <= x[i+1]
if a == True:
y = y + str(x[i])
else:
y = y + str(x[i])
z.append(y) # fill the list
y = ''
# search of 1st longest string
L = len(max(z,key=len)) # key=len takes length in consideration
for i in range(0,len(z)):
a = len(z[i])
if a == L:
print 'Longest substring in alphabetical order is:' + str(z[i])
break

first_seq=s[0]
break_seq=s[0]
current = s[0]
for i in range(0,len(s)-1):
if s[i]<=s[i+1]:
first_seq = first_seq + s[i+1]
if len(first_seq) > len(current):
current = first_seq
else:
first_seq = s[i+1]
break_seq = first_seq
print("Longest substring in alphabetical order is: ", current)