Competitive Programming in Ruby (101)

Transcript

1. Compe&&ve Programming in Ruby (101) RubyKaigi 2016 Kyoto A1er Party LT (2016-09-10) @yhara (Yutaka Hara) RubyKaigi 2016 Kyoto LT (2016-09-10) 1
2. RubyKaigi 2016 Kyoto LT (2016-09-10) 2
3. Recently I'm trying Compe22ve Programming with my colleagues RubyKaigi 2016 Kyoto LT (2016-09-10) 3
4. Compe&&ve Programming RubyKaigi 2016 Kyoto LT (2016-09-10) 4
5. Programming contest RubyKaigi 2016 Kyoto LT (2016-09-10) 5
6. Write a program fast and correctly RubyKaigi 2016 Kyoto LT (2016-09-10) 6
7. Need C(++, #) or Java? RubyKaigi 2016 Kyoto LT (2016-09-10) 7
8. You can use Ruby too! RubyKaigi 2016 Kyoto LT (2016-09-10) 8
9. Sites which supports Ruby • Sphere Online Judge • Aizu Online Judge • yukicoder • AtCoder ←Today's topic RubyKaigi 2016 Kyoto LT (2016-09-10) 9
10. atcoder.jp • AtCoder Grand Contest • AtCoder Regular Contest • AtCoder Beginner Contest • AtCoder Typical Contest RubyKaigi 2016 Kyoto LT (2016-09-10) 10
11. Don't join the contest RubyKaigi 2016 Kyoto LT (2016-09-10) 11
12. Try previous contests first ! RubyKaigi 2016 Kyoto LT (2016-09-10) 12
13. ! • Any%me • No %me limit RubyKaigi 2016 Kyoto LT (2016-09-10) 13
14. • AtCoder Grand Contest • AtCoder Regular Contest • AtCoder Beginner Contest • AtCoder Typical Contest RubyKaigi 2016 Kyoto LT (2016-09-10) 14
15. AtCoder Beginner Contest • A: Very easy • B: Easy • C: Easy? • D: Not really easy RubyKaigi 2016 Kyoto LT (2016-09-10) 15
16. But Ruby is slow...? ! RubyKaigi 2016 Kyoto LT (2016-09-10) 16
17. No problem! RubyKaigi 2016 Kyoto LT (2016-09-10) 17
18. Algorithm Ma-ers ! RubyKaigi 2016 Kyoto LT (2016-09-10) 18
19. Example: one-line Reversi RubyKaigi 2016 Kyoto LT (2016-09-10) 19
20. one-line Reversi • Given N pieces, flip Q ranges • Calculate the final state ••••••••• 1..4 2..6 8..9 ɹɹ↓ ◦•••◦◦•◦◦ RubyKaigi 2016 Kyoto LT (2016-09-10) 20
21. Just flipping each pieces? ranges.each do |r| r.each do |i| line[i] = !line[i] end end RubyKaigi 2016 Kyoto LT (2016-09-10) 21
22. RubyKaigi 2016 Kyoto LT (2016-09-10) 22
23. 200,000 pieces ! 200,000 ranges ! RubyKaigi 2016 Kyoto LT (2016-09-10) 23
24. Billions of flips ! ranges.each do |r| # <- 200,000 times r.each do |i| # <- 50,000 times or so line[i] = !line[i] end end RubyKaigi 2016 Kyoto LT (2016-09-10) 24
25. ⏰ Time Limit = 2 sec. RubyKaigi 2016 Kyoto LT (2016-09-10) 25
26. Be#er algorithm Memorize where color changes 10001 23005 ɹɹɹɹ↓ɹɹ↓ •••...•◦...◦••• RubyKaigi 2016 Kyoto LT (2016-09-10) 26
27. Passed! ! RubyKaigi 2016 Kyoto LT (2016-09-10) 27
28. You can try Compe//ve Prograaming in Ruby ! (at least for beginner contest) RubyKaigi 2016 Kyoto LT (2016-09-10) 28
29. ! BTW ! RubyKaigi 2016 Kyoto LT (2016-09-10) 29
30. RubyKaigi 2016 Kyoto LT (2016-09-10) 30
31. ABC037-D • I couldn't pass with Ruby ! • Traversing 1000x1000 maze • Maybe with Ruby3...? RubyKaigi 2016 Kyoto LT (2016-09-10) 31
32. Crystal passes ※CrystalɿRuby-like sta0cally typed language RubyKaigi 2016 Kyoto LT (2016-09-10) 32
33. Pypy2 passes ※Pypy2ɿFaster Python implemanta2on RubyKaigi 2016 Kyoto LT (2016-09-10) 33
34. Python3 passes!? ! RubyKaigi 2016 Kyoto LT (2016-09-10) 34
35. RubyKaigi 2016 Kyoto LT (2016-09-10) 35
36. RubyKaigi 2016 Kyoto LT (2016-09-10) 36
37. RubyKaigi 2016 Kyoto LT (2016-09-10) 37
38. (DON'T TRY THIS AT HOME !) RubyKaigi 2016 Kyoto LT (2016-09-10) 38