Problem Link
Author: Vipul Kumar
Editorialist: Vipul Kumar
DIFFICULTY:
EASY-MEDIUM
PREREQUISITES:
Polynomial functions , XOR Operator etc.
PROBLEM:
Find Encryption/Decryption depending on case
For 1, find Encryption and for 0 , find Decryption
Encryption rule :-
Step 1 :- f(x)=Ax+By+C
Step 2 :- f(x) XOR (index value)
QUICK EXPLANATION:
For getting first level of encryption put ASCII of each character of message into the given function f(x)=Ax+By+C and obtain f(x) Eg. For 1st level of encryption
(value of A) * ( 1st character of message) + (value of B) * (1st character of message) + (value of C) = f(x)
For 2nd level of encryption XOR obtained f(x) with message’s index value
Obtained f(x) XOR 1 (index value i.e 1 in this case) = Encrypted code
For Decryption,
For 1st level of decryption
XOR obtained f(x) with message’s index value
Obtained f(x) XOR 1 (index value i.e 1 in this case) = Y
For 2nd level of decryption
(value of A) * ( 1st character of message) + (value of B) * (1st character of message) + (value of C) = Y
AUTHOR’S AND TESTER’S SOLUTIONS:
Author’s solution can be found here.
Editorialist’s solution can be found here.