Algorithms Review

What is the speedup of the parallel solution's total algorithm time? A sequential algorithm is broken into three stages with the following set of times: Sequential Algorithm Time - Download stage: 1 minute - Sorting stage: 6 minutes - Upload stage: 1 minute A parallel version of the algorithm completes the sorting stage in parallel, leading to a new set of times: Parallel Algorithm Time - Download stage: 1 minute - Sorting stage: 2 minutes - Upload stage: 1 minute

• 6 minutes

• 4 minutes

• 2

• 3

Which of the following best describes the impacts of running the parallel algorithm on an even larger number of computers? A software company used to run an algorithm sequentially on one server. As more users start using their app, the company decided to rewrite the program to be parallel. It is now run on four separate servers instead of one. Thanks to the use of a parallel algorithm, the same process that used to take 40 minutes to run now only requires 20 minutes. The company is considering purchasing additional computers to decrease the time the program runs even further.

• The algorithm will likely require more time since it is now being run sequentially on more computers.

• The algorithm will likely require the same amount of time to run because it is processing the same amount of data.

• The algorithm will likely require less time to run though the improvements in efficiency will not be as significant as before.

• The algorithm is unlikely to still run since parallel algorithms are not designed to scale to additional computers.

Which of the following are benefits of parallel and distributed computing? I. Distributed computing improves the speed at which an individual computer executes a program II. Parallel computing scales more effectively than sequential computing III. Distributed computing allows larger problems to be solved quicker

• I. only

• I. and II

• II. and III

• I. II. and III

What is the maximum number of iterations needed to find the item? A computer is performing a binary search on the sorted list of 7 numbers below. [1, 5, 20, 50, 51, 80, 99]

• 1

• 3

• 6

• 7

Which of the following best describes whether their teacher should use a linear or a binary search? A group of students writes their names and unique student ID numbers on sheets of paper. The sheets are then randomly placed in a stack. Their teacher is looking to see if a specific ID number is included in the stack.

• The teacher could use either type of search though the linear search is likely to be faster

• The teacher could use either type of search though the binary search is likely to be faster

• Neither type of search will work since the data is numeric

• Only the linear search will work since the data has not been sorted

Which of the following algorithms is the same as the flowchart shown below?

• A. myNum ← RANDOM(1,10) IF (myNum > 8) { DISPLAY(“Done”) } ELSE { DISPLAY(myNum) }

• B. myNum ← RANDOM(1,10) REPEAT UNTIL (myNum > 8) { DISPLAY(myNum) myNum ← RANDOM(1,10) } DISPLAY("Done")

• C. myNum ← RANDOM(1,10) IF (myNum < 8) { DISPLAY(“Done”) } ELSE { DISPLAY(myNum) }

• D. myNum ← RANDOM(1,10) REPEAT UNTIL (myNum > 8) { DISPLAY(“Done”) } DISPLAY(myNum)

Which concept does this algorithm BEST demonstrate? The following algorithm is followed by a person every morning when they get up from bed to go to school: 1. Wake up 2. Brush teeth 3. Put on shirt 4. Put on pants 5. Put on socks 6. Put on shoes 7. Tie shoes

• Sequencing

• Selection

• Iteration

• Execution

Which of the following is true of algorithms?

• Algorithms may have an infinite set of instructions

• Algorithms must be expressed using a programming language

• Every algorithm can be constructed using combinations of sequencing, selection, and iteration

• Every problem can be solved with an algorithm

Which of the following is most efficient? This graph shows the efficiencies of two different algorithms that solve the same problem.

• These algorithms are equally efficient

• Algorithm A is more efficient than algorithm B

• Algorithm B is more efficient than algorithm A

• The algorithms have different efficiencies depending on the input size

Which principle does this decision best demonstrate? A school is creating class schedules for its students. The students submit their requested courses and then a program will be designed to find the optimal schedule for all students. The school has determined that finding the absolute best schedule cannot be solved in a reasonable time. Instead they have decided to use a simpler algorithm that produces a good but non-optimal schedule in a more reasonable amount of time.

• Unreasonable algorithms may sometimes also be undecidable

• Heuristics can be used to solve some problems for which no reasonable algorithm exists

• Two algorithms that solve the same problem must also have the same efficiency

• Approximate solutions are often identical to optimal solutions