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Python Dictionary to find mirror characters in a string

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  • Difficulty Level : Easy
  • Last Updated : 28 Jul, 2022
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Given a string and a number N, we need to mirror the characters from the N-th position up to the length of the string in alphabetical order. In mirror operation, we change ‘a’ to ‘z’, ‘b’ to ‘y’, and so on.

Examples: 

Input : N = 3
        paradox
Output : paizwlc
We mirror characters from position 3 to end.

Input : N = 6
        pneumonia
Output : pneumlmrz

We have an existing solution for this problem please refer to Mirror characters of a string link. We can solve this problem in Python using Dictionary Data Structure. The mirror value of ‘a’ is ‘z’,’b’ is ‘y’, etc, so we create a dictionary data structure and one-to-one map reverse sequence of alphabets onto the original sequence of alphabets. Now traverse characters from length k in given string and change characters into their mirror value using a dictionary.

Implementation:

Python3




# function to mirror characters of a string
 
def mirrorChars(input,k):
 
    # create dictionary
    original = 'abcdefghijklmnopqrstuvwxyz'
    reverse = 'zyxwvutsrqponmlkjihgfedcba'
    dictChars = dict(zip(original,reverse))
 
    # separate out string after length k to change
    # characters in mirror
    prefix = input[0:k-1]
    suffix = input[k-1:]
    mirror = ''
 
    # change into mirror
    for i in range(0,len(suffix)):
         mirror = mirror + dictChars[suffix[i]]
 
    # concat prefix and mirrored part
    print (prefix+mirror)
          
# Driver program
if __name__ == "__main__":
    input = 'paradox'
    k = 3
    mirrorChars(input,k)

Output

paizwlc

Time complexity: O(n)
Auxiliary Space: O(n)

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