Quiz — Lecture 22

Section A from memory, one line each. Section B shows your reasoning - marks are for method, not final answers. Answers are discussed in class; the exit ticket goes on a card.

Section A

A1. What two parts must every recursive function have?

A2. What proves a recursion terminates?

A3. Why is power-by-halving O(log n)?

A4. What are overlapping subproblems?

Section B

B1. Trace dsum(49206): calls and unwind.

B2. ways(8) = ? and what does memoisation change (conceptually)?

Exit ticket

Answer one of these on your card in 60 seconds (choose any one):

1. What grounds a recursion?

1. When does a table beat the tree?

1. What did cs-087 buy with halving?

Homework

• Before: skim the four student pages; attempt case 1 on paper.
• After: write a five-line pseudocode solution for any case you did not
• Enrichment (optional): the stretch question on each case page.