I don't think that checking the None's at the end of the isPalindrome are neccessary

Update problem description constraint

My solution

I think there is a slightly simpler solution (again I feel the official solution code adds extra confusion)

Solution should be different for odd and even length

Simplest soluiton using recursion

No need to check head != null (refer to the attached image)because in 1st case (...

The second half becomes its own linked list and the reverse back at the end does...

This does not look like it reverts the head to its original form.For input [1,2,...