Question

1. Using Python, Implement a function that returns an opposite of a dictionary: In order to decrypt the encrypted text, we will use the opposite of the substitution dictionary. Opposite dictionary of a dictionary is the dictionary where each value is the key and the key is the value. For instance, for the dictionary above, its opposite dictionary is

{'I': 'A', 'T': 'B', 'R': 'C', 'A': 'D', 'N': 'E', 'S': 'F', 'L': 'G', 'O': 'H', 'M': 'I', 'W': 'J', 'U': 'K', 'K': 'L', 'E': 'M', 'H': 'N', 'B': 'O', 'C': 'P', 'D': 'Q', 'F': 'R', 'G': 'S', 'J': 'T', 'P': 'U', 'Q': 'V', 'V': 'W', 'X': 'X', 'Y': 'Y', 'Z': 'Z'}

Create a function named opposite(a_dict) which returns the opposite of a dictionary named a_dict

Answer 1

def opposite(a_dict):
    res = dict()
    for x in a_dict.keys():
        res[a_dict[x]] = x
    a_dict = res
    return a_dict

#Testing
d = {'I': 'A', 'T': 'B', 'R': 'C', 'A': 'D', 'N': 'E', 'S': 'F', 'L': 'G', 'O': 'H', 'M': 'I', 'W': 'J', 'U': 'K', 'K': 'L', 'E': 'M', 'H': 'N', 'B': 'O', 'C': 'P', 'D': 'Q', 'F': 'R', 'G': 'S', 'J': 'T', 'P': 'U', 'Q': 'V', 'V': 'W', 'X': 'X', 'Y': 'Y', 'Z': 'Z'}
print(opposite(d))

{'A': 'I', 'B': 'T', 'C': 'R', 'D': 'A', 'E': 'N', 'F': 'S', 'G': 'L', 'H': 'O', 'I': 'M', 'J': 'W', 'K': 'U', 'L': 'K', 'M': 'E', 'N': 'H', 'O': 'B', 'P': 'C', 'Q': 'D', 'R': 'F', 'S': 'G', 'T': 'J', 'U': 'P', 'V': 'Q', 'W': 'V', 'X': 'X', 'Y': 'Y', 'Z': 'Z'}