Here is the solution of Prime XOR Click Here

Here is problem solution - https://programs.programmingoneonone.com/2021/07/hackerrank-prime-XOR-problem-solution.html

what does mem[i][j] mean?

The decision in the editorial isn't quite right, is it?

mem[flag^1][j^v[i-1]]*((a[v[i-1]]+1)/2))

so it can be simplified as a*(b/2)

In integer arithmetic, this gives us an incorrect result. 10*(3/2)=10 but it should be 10*3/2=15

many Python solutions which are not fast enough but in PyPy they are

because of this i wasted a whole day assuming my algorithm is not the right one