Testing Harry

Harry thinks that he is a good coder. His friend Akash gave him a task to test his coding skills. Akash asks Harry to reverse a linked list of size $N$, with each element denoted by $A_i$. But to trick Harry he asked him to reverse the nodes of list $k$ at a time. He told him that $k$ is a positive integer and is less than or equal to the length of the linked list. Help Harry to solve this ch