Computer Science

1. 1.

   An empty stack receives PUSH(A), PUSH(B), POP(), PUSH(C), POP(). State the returned values in order and the remaining stack.

   [3 marks] · no calculator
2. 2.

   Explain why a queue is appropriate for serving print jobs in arrival order and identify the insertion and removal ends.

   [3 marks] · no calculator
3. 3.

   Insert keys 10, 17 and 24 into an empty size-7 hash table using h(k)=k mod 7 and linear probing, zero-based slots. State their final slots.

   [3 marks] · no calculator
4. 4.

   For an undirected graph with edges A-B, A-C, B-D and C-D, perform BFS from A, enqueueing unvisited neighbours alphabetically and marking on enqueue. Give visit order and shortest A-to-D edge count.

   [3 marks] · no calculator
5. 5.

   A hash table uses linear probing and search stops at an empty slot. Explain why deleting a key by simply clearing its slot can break search, and how tombstones address this.

   [4 marks] · no calculator
6. 6.

   Use Dijkstra's algorithm from A on an undirected graph: A-B=4, A-C=1, C-B=2, B-D=1, C-D=5. Determine the shortest A-to-D path and explain why the algorithm requires nonnegative edge weights.

   [4 marks] · no calculator

Original, unofficial practice questions from SubjectScout — not official past-paper questions.