Question

THANK YOU FOR ANSWERING THE 4 QUESTIONS

Q3. Create a function in Python called sum_list_div2 which takes as input a list of integers and returns the sum of the elements of the list which divide by 2.

Examples of tests in the Python interpreter:

>>> sum_list_div2 ([1,4,3,8,5])

12

>>> sum_list_div2 ([])

0

>>> sum_list_div2 ([4, -10,7])

-6

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Q5. Imagine a customer at a bank who must enter a number that represents their money. There are people who type spaces to separate the thousand, millions, etc. The bank needs this number without the spaces.

Create a function in Python named number which takes as input a string of characters s. The function returns an integer that represents the number. If s contains characters other than numbers and spaces, the function returns None. If it only contains numbers and

spaces, we assume that the spaces are well placed. For example, s might be '119 189 000' but not '1345'.

Examples of tests in the Python interpreter:

>>> number ("251")

251

>>> number ("1 abc 340")

>>> number ("1250")

1250

>>> number ("- 97,500")

-97500

>>> number ("1000 001") 1000001

>>> number ("999 999 100 102") 999999100102

>>> number ("")

0

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Q8. Create a function in Python named encrypt which takes as input a string of characters s and returns an encrypted version of s. A simple encryption system writes the message beginning with the characters at the end, in reverse order. For example, 'Hello, world' becomes 'dlrow, olleH'. To make the system more difficult to decode, the function starts when standing and at the end, at the same time. The first and last character become the first and second character in the new string, the second and penultimate character become the third and fourth, etc. For example, 'Hello, world' becomes 'dHlerlolwo', (specious characters, punctuation marks, spaces, etc. are treated the same) and '0123456789' becomes '9081726354'.

Examples of tests in the Python interpreter:

>>> encrypt ("Hello, world")

'dHlerlolwo,'

>>>> encrypt ("1234")

'4132'

>>> encrypt ("12345")

'51423'

>>> encrypt ("1")

'1'

>>> encrypt ("123")

'312'

>>> encrypt ("12")

'21'

>>> encrypt ("Secret Message")

'eSgeacsrseetM'

>>> encrypt (", '4'r")

"r, '' 4"

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Q10. This question is difficult to resolve. Use fragments of the strings (operator :) and test the equality of the two strings if necessary (s1 == s2).

A word has the property squarefree if it does not contain the same subword twice in a row. Examples:

ana is squarefree.

borborygmus is not squarefree, there are bor twice in a row.

abracadabra is squarefree.

repetitive is not squarefree because ti is repeated twice in a row.

grammar is not squarefree because m is repeated twice in a row

gaga is not squarefree because ga is repeated twice in a row

rambunctious is squarefree.

abcab is squarefree.

abacaba is squarefree.

zrtzghtghtghtq is not squarefree because ght is repeated twice in a row (three times, friends twice is enough to return False).

aa is not squarefree because a is repeated twice in a row

zatabracabrac is not squarefree because abrac is repeated twice in a row

Create a function in Python named squarefree which takes as input a string of characters s and returns True if s has the property squarefree and False otherwise.

Examples of tests in the Python interpreter:

>>> squarefree ("")

True

>>> squarefree ("a")

True

>>> squarefree ("zrtzghtghtghtq")

False

>>> squarefree ("abcab")

True

>>> squarefree ("12341341")

False

>>> squarefree ("44")

False

Answer 1

CODE FOR EVERY QUESTION WITH PROGRAM SNIPPET AND OUTPUT IS GIVEN BELOW

Q3:

CODE:

def sum_list_div2(list_of_int):

  dividebytwo=[]

  for i in list_of_int:

    if i%2==0:

      dividebytwo.append(i)

  return sum(dividebytwo)

print(sum_list_div2([1,4,3,8,5]))

CODESNIPPET

def sum_list_div2(list_of_int):
  dividebytwo=[]
  for i in list_of_int:
    if i%2==0:
      dividebytwo.append(i)
  return sum(dividebytwo)

print(sum_list_div2([1,4,3,8,5]))

OUTPUT

12

Q5.

CODE:

def number(s):

  s=s.replace(" ","") #REMOVE ALL THE SPACES IN THE STRING

  list1=list(s) #CONVERT TO LIST FOR EASY PROCESSING

  listofnum=""

  for i in list1: #SCAN EACH CHARACTER IN THE STRING

    if i.isalpha()==False: #CHECK IF THE CHARACTER IS ALPHABET OR NOT

      if i!=",": #DONT PRINT , IF FOUND IN THE STRING

        listofnum+=i

    else:

      return None #IF ALPHABET FOUND THAN RETURN NONE

  return listofnum

print(number("-1,0000 0009"))

CODE SNIPPET

def number(s):
  s=s.replace(" ","") #REMOVE ALL THE SPACES IN THE STRING
  list1=list(s) #CONVERT TO LIST FOR EASY PROCESSING
  listofnum=""
  for i in list1: #SCAN EACH CHARACTER IN THE STRING
    if i.isalpha()==False: #CHECK IF THE CHARACTER IS ALPHABET OR NOT
      if i!=",": #DONT PRINT , IF FOUND IN THE STRING
        listofnum+=i
    else:
      return None #IF ALPHABET FOUND THAN RETURN NONE
  return listofnum

print(number("-1,0000 0009"))

OUTPUT

-100000009

Q8.

CODE:

def encrypt(s):

  s=list(s) #Convert string to list so that we can process easily

  slen=len(s)-1

  encryptedtext=""

  for ind in range(len(s)): #we will take 2 points one from start and another from end to encrypt first and last letters

    if ind>slen: #check if the 2 indexes crosses each other at any point as one is moving from index 0 and another from last index of string

      break

    if ind==slen: #if string length is odd than at last both counters will point to the same element

      encryptedtext+=s[ind]

      break

    encryptedtext+=s[slen] #append letter from the front

    encryptedtext+=s[ind] #append letter from the last

    slen-=1

  return encryptedtext

print(encrypt("SecretMessage"))

print(encrypt("12345"))

CODE SNIPPET

def encrypt(s):
  s=list(s) #Convert string to list so that we can process easily
  slen=len(s)-1
  encryptedtext=""
  for ind in range(len(s)): #we will take 2 points one from start and another from end to encrypt first and last letters
    if ind>slen: #check if the 2 indexes crosses each other at any point as one is moving from index 0 and another from last index of string
      break
    if ind==slen: #if string length is odd than at last both counters will point to the same element
      encryptedtext+=s[ind]
      break
    encryptedtext+=s[slen] #append letter from the front
    encryptedtext+=s[ind] #append letter from the last
    slen-=1
  return encryptedtext
print(encrypt("SecretMessage"))
print(encrypt("12345"))

OUTPUT

eSgeacsrseetM
51423

Q10.

CODE:

def square_free(func_str):

    result = True         #CREATING A RESULT VARIABLE THAT WILL BE RETURNED

    str_len = len(func_str)     #CALCULATING THE LENGTH OF THE PASSED STRING

    for p in range(str_len):    #LOOPING THROUGH THE LENGTH OF THE STRING

        for q in range(p+1, str_len):

            if func_str[p:q] == func_str[q:q+(q-p)]: #check second occurence of every possible substring from the first index

                result = False

    return result

print(square_free("zrtzghtghtghtq"))

print(square_free("abcab"))

print(square_free("12341341"))

CODE SNIPPET

def square_free(func_str):

    result = True         #CREATING A RESULT VARIABLE THAT WILL BE RETURNED
    str_len = len(func_str)     #CALCULATING THE LENGTH OF THE PASSED STRING

    for p in range(str_len):    #LOOPING THROUGH THE LENGTH OF THE STRING
        for q in range(p+1, str_len):
            if func_str[p:q] == func_str[q:q+(q-p)]: #check second occurence of every possible substring from the first index
                result = False
    return result

print(square_free("zrtzghtghtghtq"))
print(square_free("abcab"))
print(square_free("12341341"))

OUTPUT

False
True
False

SUMMARY:

All of the above codes are witten with the comments. Hence the explaination is given in the comments. The first code gets the list of numbers and check if it is even by dividing by 2 and sum all the numbers which are divided exactly by 2. The second code finds if string contains any alphabet or not and if found than return None else the entire string with only numbers. The third code takes an input string and loops from start and maintains a variable which decrements from the last index of string. We increment and decrement in every iteration with appending the characters in encrypted text. The last code finds all the possible substrings and checks if similar another substring is found consecutively in a row or not.

Note: If you have any queries than let me know in the comments. If you find it helpful than a Like would be appreciated.