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Maybe you need to improve your English.

We need codes also!

Почему разбор только последней задачи на русском?

In problem F you may observe that one of primitive roots in nimber field of size $$$2^{2^k}$$$ is $$$2^{2^k}-1$$$ so you may precalculate some of its powers beforehand to further simplify BSGS-algorithm and take discrete logarithm with base being a primitive root. If you do so, you won't need to develop tricky multiplication algorithm as $$$64^2$$$ algo with precalc for powers of two would be enough.

Can you give a better explanation for the optimization of problem (A. Recommendations)? I got to the O(n^2) solution during the contest but couldn't improve it.

Can you please explain more on how to improve the complexity of A.Recommendations from N^2 to Nlogn.

Can someone tell me why my solution for Div1A/Div2D will TLE? I think its time complexity is nlogn.

Can anyone please explain more about the problem 1310B. thanks in advance.

Can anyone pls tell me what is wrong with my code? It gives the correct output with my editor. Solution Code: 97113733

Problem $$$D$$$ is so cool! My favorite 2300 problem I've ever solved (and I've solved 56 problems of that rating).

The tutorial of the problem F seems like Pohlig–Hellman_algorithm.

i got $$$O(n\sqrt n)$$$ complexity in task E when $$$k=2$$$.

for(int i=1;i<=n;i++)for(int j=1;j*(j+1)/2<=i;j++)ans+=f[i][j]=(f[i-j][j-1]+f[i-j*(j+1)/2][j])%mod;

insert an 1 into a; or increase all elements in a by 1.