Python – Mirror Image of String

Given a String, perform its mirror imaging, return “Not Possible” if mirror image not possible using english characters.

Input : test_str = ‘boid’ Output : doib Explanation : d replaced by b and vice-versa as being mirror images. Input : test_str = ‘gfg’ Output : Not Possible Explanation : Valid Mirror image not possible.

Method : Using loop + lookup dictionary

This is one way in which this task can be performed. In this, we construct lookup dictionary for all valid mirrorable english characters, then perform task of access from them.

Python3

# Python3 code to demonstrate working of
# Mirror Image of String
# Using Mirror Image of String

# initializing strings
test_str = 'void'

# printing original string
print("The original string is : " + str(test_str))

# initializing mirror dictionary
mir_dict = {'b':'d', 'd':'b', 'i':'i', 'o':'o', 'v':'v', 'w':'w', 'x':'x'}
res = ''

# accessing letters from dictionary
for ele in test_str:
    if ele in mir_dict:
        res += mir_dict[ele]

    # if any character not present, flagging to be invalid
    else:
        res = "Not Possible"
        break

# printing result
print("The mirror string : " + str(res))

Output

The original string is : void
The mirror string : voib

Time Complexity: O(n)

Space Complexity: O(n)

 Method 2  : using string slicing to reverse the string and a lookup dictionary to replace the mirrored characters.

 step by step approach:

Define the input string.
Define a dictionary that maps mirrored characters to their respective values.
Reverse the input string using string slicing.
Iterate over the reversed string and replace each character with its mirror image from the dictionary. If the character is not present in the dictionary, set the result string to “Not Possible” and break the loop.
Reverse the result string back to its original order.
Print the original and mirror strings.

Python3

# Python3 code to demonstrate working of
# Mirror Image of String
# Using String Slicing and Lookup Dictionary

# Define input string
test_str = 'void'

# Define mirror dictionary
mir_dict = {'b': 'd', 'd': 'b', 'i': 'i', 'o': 'o', 'v': 'v', 'w': 'w', 'x': 'x'}

# Reverse the input string
rev_str = test_str[::-1]

# Initialize result string
res = ''

# Iterate over reversed string and replace mirrored characters
for ele in rev_str:
    if ele in mir_dict:
        res += mir_dict[ele]
    else:
        res = "Not Possible"
        break

# Reverse the result string
mir_str = res[::-1]

# Print the original and mirror strings
print("The original string is : " + str(test_str))
print("The mirror string : " + str(mir_str))

Output

The original string is : void
The mirror string : voib

The time complexity of this approach is O(n) as it involves iterating over the string only once. 

The auxiliary space complexity is also O(n) because we create a new reversed string and a new mirrored string.