1. Given the head of a linked list, reverse the nodes of the list k at a time, and return the modified list.
2. If you have a 3L cup and a 5L cup and an infinite water source, how can you use these 2 cups to fill exactly 4 Litres of Water?
3. Given two sorted linked lists, merge them into one sorted linked list without using extra space.
4. How do you use UART to receive signals from a microcontroller?
5. Given the head of a linked list, rotate the list to the right by k places.