Reverse_String.py

#Given a string , we need to reverse it using recursion (and iteration)
#For example, input = "Zero To Mastery", output = "yretsaM oT oreZ"

#First we will implement the iterative solution
def iterative_reverse(string): #Here we use a second string to store the reversed version. Time and Space complexity = O(n)
    reversed_string = ''
    for i in range(len(string)):
        reversed_string = reversed_string + string[len(string)-i-1]
    return reversed_string

print(iterative_reverse("Zero To Mastery"))
#yretsaM oT oreZ

#Here we append the string backwards into the original string itself and then slice it to contain only the 2nd half,i.e.,the reversed part.
#Time complexity = O(n). Space complexity = O(n)
def second_iterative_reverse(string):
    original_length = len(string)
    for i in range(original_length):
        string = string + string[original_length - i - 1]
    string = string[original_length:]
    return string

print(second_iterative_reverse("Zero To Mastery"))
#yretsaM oT oreZ


def recursive_reverse(string):
    print(string)
    if len(string) == 0:
        return string
    else:
        return recursive_reverse(string[1:]) + string[0]

print(recursive_reverse("Zero To Mastery"))
'''
Zero To Mastery
ero To Mastery
ro To Mastery
o To Mastery
 To Mastery
To Mastery
o Mastery
 Mastery
Mastery
astery
stery
tery
ery
ry
y

yretsaM oT oreZ
'''