Answers - tcsocc.uk

1 2017 AnswersThe TCS Oxford Compu0ng ChallengePilot Year 2 Working Group for the TCS Oxford Computing Challenge 2017:Daphne Blokhuis Stuart Golodetz Peter Millican Dave Oostendorp Chris Roffey Eljakim Schrijvers Sue SentanceThe TCS Oxford Computing Challenge could not have been run this year without the generous support of Tata Consultancy Services and our National Organising Body, Oxford University. I also want to thank Dave Oostendorp who worked so hard on developing the Blockly question types we have used in this Challenge. Finally it is important to recognise all the School Coordinators who have to organise the time for the students to take part.

2 In a busy school, finding an hour for a select set of students to sit quietly in front of a computer and be supervised is not an easy task. Copyright 2017 TCS Oxford Computing Challenge Licence: CC-BY-NC-SA TCS Oxford Computing Challenge is in its pilot year. It is an online challenge that asks invited students in the UK and English-speaking International Schools around the World to solve tasks using Computational Thinking skills and then provide coded solutions. It has come about because, through the Bebras Challenge, we have become aware of the incredible talent many of our students in the UK have and we felt we had to provide something to help encourage them to develop that talent further.

3 We hope students will prepare carefully throughout the year by using resources pointed to on and the archived challenges that are made freely available for all to use. It is not a trivial task creating auto-marking computing tasks and a lot of this year has been spent developing these. We have introduced four new types of tasks that can assess a variety of solutions rather than pushing students into one supposedly correct answer. Please note that although example Answers are provided in the rest of the booklet, when it comes to programming there are usually many ways to crack a nut! On the following pages you will find the 21 tasks used in the TCS Oxford Computing Challenge 2017 pilot.

4 Above each task is noted which age groups and at what level the tasks were used. After each task there is an example answer, an explanation of how the answer could be obtained plus a section on how the tasks are related to Computational Thinking. Example Answers have been provided in either blocky or Python, and occasionally both. Unfortunately, it is not possible to provide Answers in all programming languages. Python has been chosen because it is currently the most common text-based language being taught in UK schools. We have also mapped each task to up to three Computational Thinking Skills plus a Computer Science domain.

5 This system is outlined below and is thanks to the work of Valentina Dagien , Sue Sentance and Gabriel Stupurien : Each task is assigned up to 3 Computational Thinking Skills from Abstraction (AB) Algorithmic Thinking (AL) Decomposition (DE) Evaluation (EV) Generalisation (GE) Each task is assigned one Computer Science Domain from: Algorithms and programming Data, data structures and representations Computer processes and hardware Communication and networking Interactions, systems and society Up to three Keyword Tags may also be 4 England and WalesScotlandNorthern IrelandElite: Years 12 & 13 Seniors: Years 10 & 11 Intermediate: Years 8 & 9 Juniors: Years 6 & 7 Elite Years S5 & S6 Seniors: Years S3 & S4 Intermediate: S1 & S2 Juniors: Years P6 & P7 Elite: Years 13 & 14 Seniors: Years 11 & 12 Intermediate: Years 9 & 10 Juniors: Years 7 & 8It is our sincere hope that this Computational Thinking information provided will enhance the usefulness of this booklet for Computer Science teachers and their students.

6 It is for this reason that this booklet is being distributed to as many schools as possible and being made available as a PDF with a Creative Commons licence allowing it to be shared and freely as long as it is for non-commercial purposes. The 2017 challenge was conducted in four age groups: Invited students had to have achieved in the top 10% in their age group in the previous UK Bebras Challenge. The challenge is completed online in schools under the supervision of teachers. There were 15 tasks to be attempted in 1 hour. Students were expected to attempt the first 10 tasks from Sections A and B and then try to solve one or two tasks from Section C.

7 The organisers wish to pass on a special thanks to all the teachers who have made it possible for their students to enter into this competition by taking on a huge amount of the necessary administration for us. Keep informed by visiting 5 ContentsSimple Mazepage 6 Not a Pentagonpage 7 Temperature Converterpage 8 Second Counter (a)page 9 Second Counter (b)page 10 Spiralpage 11 Cross Roadspage 12 Snakepage 13 Logo Makerpage 14 Four Squarespage 15OR gatepage 16 Wrong Treepage 18 SCSV to CSVpage 20 Mean Problempage 21 Crazy Sequencepage 23 DNApage 25An Island Landingpage 27 Adding Factorspage 28 Palindrome Hunterpage 29 Odd Parity Bitspage 31 How Many Routes?

8 Page 33 6 Juniors: Intermediates:Seniors: Elite:A A robot has to travel through a maze from the red square to the green square. Task: Write a program to solve the :One possible solutionExplanation:The solution provided for this maze requires the programmer to realise that the robot has only to move forward or left to reach its objective. As there is no limit to the number of blocks allowed, an alternative solution would be to provide a long list of steps that takes the robot to its s Computer Science:Simple MazeCT Skills - Algorithmic Thinking (AL) CS Domain - Algorithms and programming Tags - Blockly, Loops, Mazes In mobile robotics, navigation is a common problem.

9 Maze solving is not so common but requires similar Computer Thinking skills to be employed. To solve this problem, an autonomous robot is used. Mazes can be of different kinds: having loops, without any loops, grid systems or without a grid system. In this short loop maze algorithm, the robot is instructed to prioritise turning left, where possible, and otherwise to simply move forwards. 7 Explanation:It s Computer Science:CT Skills - Algorithmic Thinking (AL), Decomposition (DE), Evaluation (EV) CS Domain - Algorithms and programming Tags - Blockly, Debugging, Turtle Humans get through life by making assumptions and filtering out noise.

10 Currently, computers are not good at this. When we write programs, every detail has to be correct and everything thought of. Even with carefully designed systems this is not always possible. This makes debugging code that does unexpected things an important skill. Types of Programming Errors: Debugging: A young programmer has tried to write his first program, but he cannot understand why he gets a small triangle instead of a large pentagon. "But I have looped five times, so surely this should not make a triangle!" he says. Task: 1. Run the program without changing anything to see what is happening. 2.