merges sort

ミニ勉強会でmerge sortについて話したスライド

Transcript

1. Merge Sort Hiroki Kumamoto
2. Merge sort • ഑ྻΛ̎ͭʹ෼͚Δ • ͦΕͧΕΛιʔτʢ࠶ؼతʣ • ̎ͭΛϚʔδ͢Δ • ιʔτࡁΈͷ̎ͭͷ഑ྻΛϚʔδͯ͠ιʔτ ࡁΈͷ΋ͷΛ࡞Δͷ͸؆୯ʂ
3. Merge sort • NݸͷཁૉΛ࣋ͭ഑ྻΛιʔτ͢Δͱ͖ͷ • ൺֱͷճ਺ C (N) • C(N) <= C([N/2]) + C([N/2]) + N for N > 1 • C(1) = 0 • -> N log N • ഑ྻ΁ͷΞΫηε • A(N) <= A([N/2]) + A([N/2]) + 6N for N > 1 • A(1) = 0 • -> 6 N log N • memory࢖༻ྔ: N
4. Merge sort • Improvements • ༨෼ͳ഑ྻΛ࢖Θͣʹin-place Ϛʔδ • ࠷ॳ͸insertion sort Λ࢖͏ (7 ݸ·Ͱ) • ͢ͰʹιʔτࡁΈͳΒ్தͰεΩοϓ
5. • Visualize Demo • http://kumabook.github.io/playground/ index.html#merge-sort