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AP Computer Science Principles Unit 3: Algorithms and Programming

12 questions

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Unit 3: Algorithms and Programming

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Question 1

Which of the following pairs BEST distinguishes a procedure from an event handler?

A.A procedure can take parameters; an event handler cannot.B.A procedure is called explicitly by other code; an event handler runs in response to a user action or system event.C.A procedure runs in parallel; an event handler runs sequentially.D.Only event handlers can have side effects on the display.

Question 2

Which of the following problems has a REASONABLE (polynomial-time) algorithm, and which is considered to have only UNREASONABLE (exponential-time) algorithms for large inputs?

Problem I: Sorting a list of n numbers
Problem II: Checking all possible subsets of n items to find a subset that sums to a target value (brute-force subset sum)

A.Both problems have reasonable (polynomial-time) algorithms.B.Problem I has a reasonable algorithm (e.g., merge sort runs in O(n log n)); Problem II (brute-force) has an unreasonable exponential-time algorithm.C.Both problems have only unreasonable (exponential-time) algorithms.D.Problem I is unreasonable because you must compare every pair of elements; Problem II is reasonable because you stop as soon as you find a valid subset.

Question 3

Which of the following lists contains the elements in the correct order after a linear (sequential) search of the list [3, 7, 1, 9, 4] for the value 9?

A.The algorithm checks 9 first because it searches for the target value.B.The algorithm checks elements in the order: 3, then 7, then 1, then 9 (found).C.The algorithm checks elements in the order: 9, 4, 1, 7, 3 (reverse order).D.The algorithm sorts the list first, then searches: 1, 3, 4, 7, 9.

Question 4

A procedure double(n) returns n * 2. What is the value returned by double(double(3))?

A.6B.9C.12D.18

Question 5

What is displayed when the following pseudocode runs?

nums ← [10, 20, 30, 40, 50]
total ← 0
FOR EACH n IN nums
{
   total ← total + n
}
DISPLAY total

A.50B.100C.150D.250

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Question 6

Which of the following Boolean expressions evaluates to true?

A.(5 > 7) AND (3 = 3)B.(5 > 7) OR (3 = 3)C.NOT (3 = 3)D.(5 > 7) AND NOT (3 = 3)

Question 7

A list scores ← [85, 92, 78, 90, 65] is passed to the procedure below. What value does mystery(scores) return?

PROCEDURE mystery(list)
{
  best ← list[1]
  FOR EACH item IN list
  {
    IF (item > best)
    {
      best ← item
    }
  }
  RETURN best
}

A.65B.85C.92D.410

Question 8

What is displayed when the following pseudocode runs?

result ← 1
REPEAT 5 TIMES
{
   result ← result * 2
}
DISPLAY result

A.10B.16C.32D.64

Question 9

A delivery company needs to find a route that visits 30 cities and returns home with the lowest total distance. An exact algorithm guaranteed to find the optimal route would take an impractically long time. Which approach is MOST appropriate?

A.Use a heuristic (e.g., "always travel to the nearest unvisited city next") that finds a good — but not necessarily optimal — route quickly.B.Always use the exact algorithm because correctness matters more than speed.C.Skip the routing problem and have drivers pick routes manually.D.Use a random ordering of cities each time.

Question 10

What is displayed when the following pseudocode runs?

x ← 10
IF (x > 5)
{
  IF (x > 12)
  {
    DISPLAY "big"
  }
  ELSE
  {
    DISPLAY "medium"
  }
}
ELSE
{
  DISPLAY "small"
}

A.bigB.mediumC.smallD.big medium

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Question 11

A programmer needs to compute the area of three rectangles with different dimensions and display each area. Which approach BEST demonstrates procedural abstraction?

A.Copy and paste the multiplication and DISPLAY statements three times, hard-coding each set of dimensions.B.Write three separate procedures, one per rectangle, with no parameters.C.Write one procedure area(width, height) that returns width * height, then call it three times with different arguments.D.Use a global variable for area and reassign it inside each section.

Question 12

A student writes the following procedure header:

PROCEDURE addNumbers(a, b)

Which statement BEST describes what a and b are?

A.They are the values the procedure returns to the caller.B.They are parameters that receive the values passed in by the caller.C.They are global variables shared between all procedures.D.They are constants whose values cannot change.

AP Computer Science Principles Unit 3: Algorithms and Programming — Free with Answer Explanations | Test Practice Hub