Using Python3 (Do not use regular expressions, no tuples, no methods of string,

Question

Using Python3 (Do not use regular expressions, no tuples, no methods of string, or def.) .

Write a program called DeleteRuns. this is what the program does: ask user for a string (see prompt in examples below) the input can be any string. Examples: 123 1222223 122223222232222522226 axxxbyybyy 1234554321 hello 1km 1mi 1.5km 23.89mi now is the time if user enters the empty string (i.e. just press enter) the program ends and prints: goodBye! DeleteRuns is supposed to delete all adjacent repeated characters. For example: if input is: 123333 the output is 12 input: 1222342 output: 1342 input: 122233342 output: 142 if after deleting all repeated characters the resulting string has adjacent repeated characters those must be deleted too. For example: input: 1233324 output: 14 after deleting the run of 3s you would get: 1224, which itself contains a run of 2s. The final result must not have any sequence of adjacent repeated characters. Another example: input: a1234554321b output: ab Examples % DeleteRuns.py enter a string: aba aba enter a string: abcd abcd enter a string: abcc ab enter a string: abccc ab enter a string: aabc bc enter a string: aaabc bc enter a string: abbc ac enter a string: abbbc ac enter a string: aabcc b enter a string: aabbcc enter a string: xabcdeedcbay xy enter a string: goodBye!

Explanation / Answer

For a given problem statement, we have to have the functions to avoid repeated code.

Find below script in python 3 as a solution for given program.

DeleteRuns.py

# Utility functions

def TakeList(string):

x = []

for i in string:

x.append(i)

return x

def TakeString(x):

return ''.join(x)

# Recursively remove adjacent duplicates from str and returns new string.

# Previous_removed is a pointer to last removed character.

def RemoveAdjacent(string, Previous_removed):

# If length of string is 1 or 0

if len(string) == 0 or len(string) == 1:

return string

# Remove leftmost same characters and recur for remaining

# string

if string[0] == string[1]:

Previous_removed = ord(string[0])

while len(string) > 1 and string[0] == string[1]:

string = string[1:]

string = string[1:]

return RemoveAdjacent(string, Previous_removed)

# At this point, the first character is definitely different

# from its adjacent. Ignore first character and recursively

# remove characters from remaining string

rem_str = RemoveAdjacent(string[1:], Previous_removed)

# Check if the first character of the rem_string matches

# with the first character of the original string

if len(rem_str) != 0 and rem_str[0] == string[0]:

Previous_removed = ord(string[0])

return (rem_str[1:])

# If remaining string becomes empty and last removed character

# is same as first character of original string.

# This is needed for a string like "acbbcddc"

if len(rem_str) == 0 and Previous_removed == ord(string[0]):

return rem_str

# If the two first characters of str and rem_str don't match,

# append first character of str before the first character of

# rem_str.

return ([string[0]] + rem_str)

def remove(string):

Previous_removed = 0

return TakeString(RemoveAdjacent(TakeList(string), Previous_removed))

# Call Function recursively ubless hit ENTER

while True:

i = input("Input text & hit ENTER to quit: ")

if not i:

print("GoodBye")

break

print (remove(i))

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