• + 1 comment

    Hint:-

    Here total number of possibilities are 3(3N).

    M = 109+7.
    To calculate (ab)%M and we know b can be very large(3N) .
    Using Fermat's little theorem (a(M-1))%M = 1, first we will do b=b%(M-1) and then calculate (ab)%M by using fast exponentiation.
    References :-
    1. Codechef Discussion
    2. Geeksforgeeks

    • + 1 comment

      sorry bro,i cannot understand how it is 3 to the power 3 to the power N. can u explain me?

      • + 1 comment

        Hi,

        For user input n, there would be 3^n blocks. Each of these 3^n blocks can be coloured in 3 ways.

        You can color1 block in 3 ways, You can color 2 blocks in 3*3 (3^2) ways.. .. You can color 3^n blocks in 3^(3^n)) ways.

        • + 0 comments

          thanks alot......