Mixed review of lists

Questions 1 to 5 of 8

1. 1. Two lists are built separately with from_list(1, 2) and from_list(1, 2). Both print 1 -> 2. Why does length_difference return None for them?

   The two lists share no node objects. The method compares references with is, and separate nodes are different objects even when their values match.The values differ between the lists, so the method returns None at the first mismatch.The lengths are equal, so the two pointers can never reach the same step.The method only checks the two heads, so it returns None whenever the heads hold different nodes.
2. 2. Put the steps of the length-difference intersection method in the order they run.

   Use the arrows to put the steps in order.

   1. 1.Move the head of the longer list forward by the difference in lengths.↑↓
   2. 2.Walk both pointers forward one node at a time.↑↓
   3. 3.Stop at the first node where the two pointers are the same object, and return it.↑↓
   4. 4.Count the nodes in each list.↑↓
3. 3. What does this code print? ``python head = from_values(1, 2, 3, 4, 5, 6) print(to_list(rotate_right(head, 8))) ` Use rotate_right, from_values and to_list from the rotation lesson, with k` set to 8.

   [3, 4, 5, 6, 1, 2][1, 2, 3, 4, 5, 6][5, 6, 1, 2, 3, 4][6, 1, 2, 3, 4, 5]
4. 4. In reverse_in_groups, why does prev start at group_next instead of None?

   The last node of the block then points at the node after the block, so no link is lost.It stops the loop after one node, so the block is reversed in one step.The block is reversed in place without needing the variable cur.It lets the code detect that the block is short before the reversal starts.
5. 5. In the two-pointer intersection method, why does pa become b when pa is None, as in pa = b if pa is None else pa.next?

   It makes the pointer skip the first node of its own list.It compares the values at each step, so the walk stops at the first repeated value.It sends the pointer to the head of the other list, so both pointers walk the same total number of nodes.It ends the loop as soon as either pointer reaches None.