Linked List — Reasoning Check

1. While reversing 1→2→3, a program assigns cur.Next=prev and then advances cur=cur.Next. Why can it lose the remaining nodes?

Select one answer.

Reversal requires allocating new nodes because Next cannot be changed safely. prev must always point to the original head, so changing it loses the list. cur.Next now leads into the reversed prefix, so the original successor must have been saved first.

2. Reverse groups of k=2 in 1→2→3→4→5. What is the value of the fourth node in the result? Enter one integer.

3. Two distinct nodes both contain value 7 and both point Random to the first node. What must a deep copy preserve?

Select one answer.

Two distinct clone nodes, with both Random links pointing to the clone of the first node. Two clone nodes whose Random links still point to the original first node. One shared clone node because both original values are 7.

4. An LRU cache of capacity 2 performs Put(4,40), Put(5,50), Put(4,44), Put(6,60). Which key is evicted? Enter one integer.

5. In a three-node list A→B→C→nil, remove the third node from the end using a dummy predecessor. Which edge must be changed?

Select one answer.

B.Next must become nil. A.Next must become C. dummy.Next must become B.

6. What value is stored in the last node when adding reverse-order digit lists [9,9,9] and [1]? Enter one integer.