JAVA question

[5 points] Given a doubly-linked list, how do you find its middle node? Given a singly

linked list, how do you find its middle node? When there is an even number of nodes, report the node slightly left of the center as the middle. (Hint: For a singly linked list, use a fast and a slow pointer. The fast pointer moves at a speed twice as that of the slow pointer.)

Please write the pseudocodes. For every algorithm you describe, please also give its time complexity.