Competitive programming

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What is competitive programming and some ways to prepare for online competitions

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Competitive programming

  1. 1. COMPETITIVE PROGRAMMING<br />Ishani Parekh<br />
  2. 2. What is it ?<br />Writing programs to solve problems in a contest environment. <br />One has limited time to solve problems. Ranging from a few hours to a few days. <br />Team participation or Individual.<br />
  3. 3. What do these contests test ?<br />Algorithm Skills (Must !)<br />Basic Math Skills<br />Programming Skills<br />Speed (Good typing speed helps)<br />Creativity<br />Debugging Skills (For challenge phase)<br />
  4. 4. Some Prestigious contests<br />ACM – ICPC<br />Google Code Jam<br />Topcoder Open<br />Facebook Hacker Cup (Recent)<br />
  5. 5.
  6. 6. ACM - ICPC<br />It is like the Olympics for Programming.<br />Students who win these contests are some of the finest brains in the world and are instantly recognized by top institutions (companies, academia)<br />
  7. 7. Rules -1<br />Online Contest - National level (around 1000 teams)<br />Onsite Contest - National level (around 130 teams)<br />World Finals (around 2-3 teams selected from India)<br />
  8. 8. Rules - 2<br />Team Contest (max size:3)<br />Languages : C/C++/Java<br />Time : 5 hrs<br />One machine<br />Set of around 10 problems.<br />Ranking is based on number of problems solved with penalty for wrong submissions.<br />
  9. 9. What do you gain?<br />Improve your logical and analytical skills.<br />Good point to mention in CV.<br />Improve your network of friends who are also interesting in programming.<br />Recognition.<br />Most importantly, have fun. Onsite contests also plan excursions.<br />
  10. 10. Where to practice<br />Topcoder (highly recommended)<br />SPOJ <br />Codeforces<br />Codechef<br />UVa<br />USACO<br />
  11. 11. A Typical Problem<br />http://www.spoj.pl/problems/AGGRCOW/<br />Problem Statement<br />Input<br />Output<br />Constraints (you don’t check for this. It will be satisfied by the input)<br />Time Limit (typically ~10^7 operations under 1s)<br />Memory Limit (typically 64 MB at runtime)<br />
  12. 12. Contest System<br />Each problem has a problem setter.<br />He writes the problem, generates input test cases and their corresponding correct outputs.<br />Your program takes input and generates output in the format specified in the problem.<br />Outputs of your program will be compared with the correct outputs.<br />
  13. 13. Responses from the judge<br />http://www.spoj.pl/status/<br />Accepted<br />Wrong Answer<br />Time Limit Exceeded<br />Compilation error<br />Segmentation fault (SIGSEGV)<br />…<br />…<br />
  14. 14. Tips for good performance<br />Maintain pre-written templates for<br />Standard algorithms <br />Necessary headers, functions etc. (eg. all #includes and macros in c++)<br />Indent your code <br />If you use Vim editor, configure your .vimrc file for your programming language. Use the visual mode to indent code. <br />
  15. 15. Tips for good performance<br />Use functions/methods wherever possible to avoid repetition of code.<br />Solve the problem on paper first. Then only code. <br />Write test cases for the problem and test your logic and program with those test cases before submitting. <br />Test your program for the worst case. Use “time” command to check the running time of your programs in linux.<br />
  16. 16. Tips for good performance<br />Know the contest rules before you compete.<br />Take risks and don’t panic .<br />Read contest editorials/explanations after the contest is over. <br />Solve your questions by<br />Thinking yourself or searching the internet.<br />Asking friends.<br />Visiting forums.<br />
  17. 17. Resources<br />Topcoder Tutorials<br />Topcoder Forums<br />Google Code Jam<br />Codechef Wiki<br />
  18. 18. Demo<br />Topcoder Arena.<br />

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