I was solving this question 1731C - Even Subarrays
I was getting TLE on test 2 until i decided to have a look a at the editorial Editorial suggested an n root n complexity answer => 186975655
which then i implemented the same in java and 237133047
i felt maybe hash map collisions could lead to this, so i tried with trie data structure as well that didnt even cross test 3
The C++ submission you linked does not use any hashmap. It just uses a couple of vectors.
Instead of hashmaps you should use arrays. Note that $$$a_i \leq n$$$, now we can use the fact that xor of a set of elements $$$\leq n$$$ is $$$\leq 2^{\lfloor \log n \rfloor + 1} - 1$$$.
So if you use an array of size $$$2^{\lfloor \log n \rfloor + 1}$$$ you would be safe. (in the official solution they have used $$$2n$$$ which is $$$> 2^{\lfloor \log n \rfloor + 1} - 1$$$).
Hashmaps are usually quite slow and take a lot of constant time, in fact some people who tried to use
unordered_mapof c++ also got TLE (you can see the editorial comment section).