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おしゃれなアルゴリズム

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Avatar for eTakazawa eTakazawa
February 22, 2020

 おしゃれなアルゴリズム

本スライドは某LT用に作成しました.厳密性より,非競プロerに向けて面白さを重視しています.
過去問題の解説です.

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eTakazawa

February 22, 2020
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  1. Question • ೖྗ - ೑ (Ґஔɼ௕͞) × Nݸ ( N

    ≦ 10^5 ) - ໢ͷ௕͞ M ( M ≦ 10^5 ) • ໨త - ֤೑ʹ͍ͭͯম͔͘ম͔ͳ͍͔બͼɼ
 ೑͕ॏͳΒͣম͚Δ௕͞ͷ૯࿨Λ࠷େԽ͠ग़ྗ   ೑1 ೑2 ೑3 ໢
  2. Question • ೖྗ - ೑ (Ґஔɼ௕͞) × Nݸ ( N

    ≦ 10^5 ) - ໢ͷ௕͞ M ( M ≦ 10^5 ) • ໨త - ֤೑ʹ͍ͭͯম͔͘ম͔ͳ͍͔બͼɼ
 ೑͕ॏͳΒͣম͚Δ௕͞ͷ૯࿨Λ࠷େԽ͠ग़ྗ   ೑1 ೑2 ೑3 ໢
  3. Question • ೖྗ - ೑ (Ґஔɼ௕͞) × Nݸ ( N

    ≦ 10^5 ) - ໢ͷ௕͞ M ( M ≦ 10^5 ) • ໨త - ֤೑ʹ͍ͭͯম͔͘ম͔ͳ͍͔બͼɼ
 ೑͕ॏͳΒͣম͚Δ௕͞ͷ૯࿨Λ࠷େԽ͠ग़ྗ   ೑1 ೑2 ೑3 ໢
  4.   • ”೑͕ॏͳ͍ͬͯΔ” or ”Կ΋ͳ͍” ۠ؒ
 ͸௕͕͞Ք͛ͳ͍ • ”શମͷ௕͞M

    ʔ ম͚ͳ͍۠ؒͷ௕͞”
 Ͱ౴͕͑ग़Δ ղ๏Λࢧ͑Δߟ͑ํ ম͚Δ෦෼Λ௕͘ → ম͚ͳ͍෦෼Λ୹͘
  5. ղ๏   1 1 1 1 ೑1 ೑2 ɹɹͱɹɹΛম͘৔߹Λදݱ

    ೑1 ೑2 ”Կ΋ͳ͍”۠ؒ ”ॏͳ͍ͬͯΔ”۠ؒ
  6. ղ๏ ·ͱΊ   1 1 1 1 1 1

    1 1 1 1 1 ࠨ୺͔Βӈ୺΁ͷܦ࿏্ͷίετͷ૯࿨ ʹ ম͚ͳ͍෦෼ͷ௕͞
  7. ղ๏ ·ͱΊ   1 1 1 1 1 1

    1 1 1 1 1 ͭ·Γɼࠨ୺͔Βӈ୺΁ͷ࠷୹ܦ࿏ ʹ ম͚ͳ͍෦෼ͷ௕͕͞࠷খͷ೑ͷબͼํ
  8. ղ๏ ·ͱΊ   1 1 1 1 1 1

    1 1 1 1 1 ͭ·Γɼ࠷୹ܦ࿏௕͕෼͔Ε͹ྑ͍ → ؆୯ʂ
  9. ղ๏ ·ͱΊ   1 1 1 1 1 1

    1 1 1 1 1 ͭ·Γɼ࠷୹ܦ࿏௕͕෼͔Ε͹ྑ͍ → ؆୯ʂ ܭࢉྔతʹ͸ɿ શ୳ࡧ O(2^N) → ຊख๏ O((M+N)logM)
  10. ͋ͱ͕͖ • ࠷୹ܦ࿏໰୊ʹؼணͰ͖ͯ࠷ߴʹ͓͠ΌΕ - ম೑ʹߦ͘ͱ͖͸ࢥ͍ग़ͯ͠Ͷ • ໘നΈΛײͨ͡ํ͸ڝϓϩ΍͍ͬͯͩ͘͞ • ࠷େԽΛ͢Δ࣌͸Կ͔ͷ࠷খԽʹ
 ஔ͖׵͑ΒΕͳ͍͔ߟ͑Δ

    - “࠷େԽΛ࠷খԽʹมܗͯ͠ɼ࠷খΧοτʹؼண” ͸ׂͱయܕΒ͍͠ʢࢀߟɿ೩΍͢ຒΊΔ໰୊ʣ   https://www.slideshare.net/shindannin/project-selection-problem
  11. ͓·͚ • ൈ͚͍ͯΔେࣄͳߟ࡯ - ઌͷܦ࿏Ͱ͸ɼ3ຕҎ্೑͕ॏͳΔબͼํΛ
 දݱͰ͖ͳ͍ - ॏͳͬͨ෦෼Λ༨ܭʹίετͱͯ͠Χ΢ϯτͯ͠ ͠·͏ɽ͕ɼͦ΋ͦ΋3ຕҎ্ॏͳΔ೑ͷબͼํ ͸ɼ࠷దղʹͳΓಘͳ͍

    • ެࣜϖʔδͷղઆΛಡΜͰ͍ͩ͘͞ • ࢲ͕ॻ͍ͨίʔυ͸ͪ͜Β   https://www.slideshare.net/chokudai/code-festival-2015-final https://code-festival-2015-final-open.contest.atcoder.jp/submissions/10197952