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
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
3.5
アルゴリズム例
■
45
追加凸包点が間違っていることを示すので、その点を取り除く。
グラハム走査
Graham's Scan
最良 平均 最悪
O(n log n)
graham(P)
low = y
座標最小
in P
の点
❶
そのような点が複数あれば、
x
座標が最小の点を選ぶ。
P
から
low
を除く
low
に対する極角の降順で
P
をソートする
❷
P[0]
は最大極角、
P[n-2]
は最小極角。
hull = {P[n-2], low}
❸
最小極角と
low
から始めて時計回りに凸包を作る。
for i = 0 to n-1 do
while (isLeftTurn(secondLast(hull), last(hull), P[i])) do
点
last
を
hull
から取り除く
❹
左回りは最後の凸包点を取り除かねばならないことを示す
。
P[i]
を
hull
に追加
重複した点
last
を取り除く
❺
P[n-2]
だから。
return hull
3.5.2
入出力
凸包問題インスタンスは点集合
P
で定義される。
出力は、凸包を時計回りにたどったものを表す点
(x, y)
列。どの点が先頭かは関
係ない。
3.5.3
文脈
このアルゴリズムは、デカルト座標の点集合に適している。例えば、もし、点集
合が異なる座標系を用いていて、
y
値の増加が平面上でより低い点を示すなら、ア
ルゴリズムはその系に従って
low
を計算すべきである。点を極角でソートするには、
三角関数の演算が必要となる。
3.5.4
解
この問 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.