December 2016
Intermediate to advanced
440 pages
9h 44m
Japanese
Content preview from アルゴリズムクイックリファレンス 第2版
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178
■
6
章 グラフアルゴリズム
開データセット（
http:
//
www.iwr.uni-heidelberg.de
/
groups
/
comopt
/
software
/
TSPLIB95
/
）からとられたものだ。このデータに対して、各アリゴリズムを
100
回
実行し最良と最悪を棄却した。表には残りの
98
回の平均が含まれる。優先度付き
キューを用いた場合と
密グラフ用ダイクストラ法
に実装の違いはほとんどないが、
密
グラフ用ダイクストラ法
では性能が大幅に改善されていることがわかる。右端の列
は同じ問題に対する
ベルマン
-
フォード法
の性能を示している。ただし、他のアルゴ
リズムと異なり節点数の増加に対して性能の低下が激しいため、
5
回の実行の平均
を示した。
ベルマン
-
フォード法
の疎グラフに対する絶対性能は妥当だが、他のアル
ゴリズムの結果と相対的に比べると、密グラフに対して
ベルマン
-
フォード法
を使用
するのは明らかに誤りであることがわかる。もちろん、負の重みの辺
があり、この
アルゴリズムを使わなければならない場合は別だが。
表6-2 密グラフの単一始点最短経路を計算する時間（秒）
V E
PQによる
ダイクストラ法
DG用に最適化された
ダイクストラ法
ベルマン- フォード
法
980 479,710 0.0681 0.0050 0.1730
1,621 1,313,010 0.2087 0.0146 0.5090
6,117 18,705,786 3.9399 0.2056 39.6780
7,663 29,356,953 7.
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.