Computational Thinking · Quiz 2 · May 2026

This is a reference card showing the schemas and sample rows of Scores, Words, Library, Olympics and Shopping Bills. It supplies context for later pseudocode questions rather than asking for a computed result. Use the field names and row meanings when tracing the later algorithms; the displayed ellipses indicate omitted rows, not a complete dataset. **Answer: A.** A: **Correct:** The source selects the acknowledgement that useful dataset information is supplied. B: **Incorrect:** This describes its reference role too, but is not the source's selected administrative acknowledgement; these are not competing computational answers.

For each city, First and Second track the two largest student totals and Count tracks how many student rows the city has. A new maximum shifts the previous maximum into Second; other totals can improve Second. Equal highest totals are allowed, so these are the top two student scores, not necessarily distinct numerical values. The final test requires Count>=2 and First-Second<=10. Thus L contains cities whose top two totals differ by at most 10. **Answer: A.** A: **Correct:** Matches the two stored maxima and the final difference test. B: **Incorrect:** The algorithm does not compare the maximum with the minimum; lower students can be far behind. C: **Incorrect:** The final comparison is at most 10, not greater than 10. D: **Incorrect:** The tracked maxima are updated throughout the scan, not limited to the first two rows.

update ignores every non-English book. For an English book, it groups by publisher and stores its name and year. An existing entry is replaced only if the new year is smaller, so each entry represents an earliest English book for that publisher. If several books share that earliest year, the first encountered is retained because the comparison is strict. **Answer: A.** A: **Correct:** Correctly identifies the per-publisher earliest English book information. B: **Incorrect:** A smaller year replaces the entry, so it tracks earliest rather than latest. C: **Incorrect:** No book count is accumulated. D: **Incorrect:** Non-English books never enter the selection.

Each row in Words is examined, and count increases exactly when X.LetterCount>=8. There is no part-of-speech filter, sentence grouping or uniqueness test. Thus count measures word occurrences with at least eight letters, including repeated occurrences if the dataset has them. **Answer: A.** A: **Correct:** Precisely matches the only condition and one increment per qualifying row. B: **Incorrect:** There is no requirement that PartOfSpeech be Noun. C: **Incorrect:** LetterCount concerns letters in a word, not the number of words in a sentence. D: **Incorrect:** There is no deduplication of equal words.

Each iteration appends the current last element to ans, then init(L) removes that last element from L. For [3,8,1,6], the extracted sequence is 6,1,8,3. Thus the function returns [6,1,8,3], a reversal of the input list. **Answer: B.** A: **Incorrect:** This is the original order, not the removal order. B: **Correct:** Correctly lists successive last elements 6,1,8,3. C: **Incorrect:** Omits the first original element and does not reverse the others. D: **Incorrect:** Keeps an incorrect order for the middle extracted values.

For each category, Amount accumulates item costs and Units accumulates purchased quantities across all bills. Value=Amount/Units is therefore total expenditure per purchased unit. If cost=quantity×unit price, this is a quantity-weighted average of unit prices, not an unweighted average of distinct item names. It assumes a category being divided has positive total quantity. **Answer: B.** A: **Incorrect:** Distinct item names are not deduplicated or equally weighted. B: **Correct:** Total cost divided by total units gives the average unit price across purchased units. C: **Incorrect:** It groups item costs by category, not whole-bill totals. D: **Incorrect:** Total cost is Amount; Value divides that by Units.

For each item name and shop, Price stores the first observed price and Flag starts False. On any later occurrence with a different price, Flag becomes True and is never reset. Thus True means that at least two observed prices differ for that item at that shop. Multiple bills alone are insufficient if every price stays equal. **Answer: C.** A: **Incorrect:** Constant price leaves Flag False. B: **Incorrect:** Two or more bills can still all have the same price. C: **Correct:** A differing observed price sets the persistent variation flag True. D: **Incorrect:** A single occurrence only initialises Flag=False.

Only nouns enter checkWord. It compares symmetric character pairs while i<j, counting total pairs t and matching pairs m. When m=t, every compared pair agrees, so the noun is a palindrome and P increases. When m=0, no symmetric pair agrees, so the word enters L. For a one-letter noun, there are no pairs: m=t=0, so it increases P and also enters L. The centre letter of an odd-length word is not compared with itself. **Answer: A, B, D.** A: **Correct:** m=t means every symmetric pair matches, the palindrome condition. B: **Correct:** m=0 means no compared symmetric pair matches, and the outer filter guarantees a noun. C: **Incorrect:** The outer noun test prevents non-nouns from reaching this increment. D: **Correct:** A one-letter noun has zero matching and zero total pairs, so m=t holds.

S must begin as an empty list, not the string 'None'. When a matching-shop card belongs to a customer not yet present, append the customer's name, not the shop name. Finally isPresent must initialise present=False; it should return True only if its search finds the name. The condition on line 6, the equality check on line 18, and setting True on line 19 are appropriate once those errors are repaired. **Answer: A, C, D.** A: **Correct:** Line 2 should initialise S as a list. B: **Incorrect:** Checking not isPresent is the correct way to prevent duplicate customers. C: **Correct:** Line 7 must append X.CustomerName, not X.ShopName. D: **Correct:** Line 16 must start present as False; otherwise every search reports success. E: **Incorrect:** Line 18 correctly compares the current element with the sought name. F: **Incorrect:** Line 19 correctly marks a found name as present. G: **Incorrect:** The initialisation and append errors prevent the required result.

A receives every student's unique sequence number when Mathematics>=90. B is appended only inside that same block and additionally requires Total>=270. Therefore B is a subset of A, and length(B)<=length(A). The total threshold alone does not populate B unless the Mathematics condition also holds. **Answer: A, B, D.** A: **Correct:** Every append to B occurs within the condition that also appends to A. B: **Correct:** A's exact membership test is Mathematics>=90. C: **Incorrect:** B need not be as large as A; students can satisfy the Mathematics test but fail the total test. D: **Correct:** Subset membership and unique identifiers guarantee length(A)>=length(B).

Each genre's Authors list records an author only on the first encountered book for that author in the genre. Pages likewise gains that book's pages only on the first encounter. Thus Authors has no duplicates and Pages sums one first-encountered book per author, rather than every book. If an author's page counts vary, changing row order can change which book contributes. No publication-year comparison is performed. **Answer: A, C, D.** A: **Correct:** Membership checking prevents an author's repeated insertion within a genre. B: **Incorrect:** Later books by an already-listed author do not add their pages. C: **Correct:** Only the first encountered book by that author can contribute. D: **Correct:** Different first-encountered books can produce different page sums. E: **Incorrect:** There is no year comparison selecting the latest book.

The procedure adds the last element of each inner list whose length is at least two. [2] is skipped. [5,1] contributes 1; [4,7,3] contributes 3; [6,8] contributes 8. Total=1+3+8=12. The test concerns each inner list's length, not its numeric values. **Answer: 12.**

Process complete sentences separately and compare their distinct normalised words with positiveList. Sentence 1 has none. Sentence 2 contains happy and awesome, so it qualifies. Sentence 3 contains nice and cool, so it qualifies. Sentence 4 contains best only, so it fails the threshold of two distinct positive words. Therefore posSen=2. Deduplication means repeating one positive word would not count as two different matches. **Answer: 2.**