September 2014
Intermediate to advanced
336 pages
7h 53m
Japanese
Content preview from アンダースタンディング コンピュテーション ―単純な機械から不可能なプログラムまで
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.
196
6
章 無からのプログラミング
SUBTRACT[x][n]
][
x
]
}][m]
} }
この
MOD
のバージョンは、再帰バージョンとまったく同じように動きます。
>>
to_integer(MOD[THREE][TWO])
=> 1
>>
to_integer(MOD[
POWER[THREE][THREE]
][
ADD[THREE][TWO]
])
=> 2
こちらの実装のほうがほぼ間違いなく単純になりますが、一般的には読みづらくなり、効率も悪くな
ります。できる限り早く停止するのではなく、常に最悪の場合の数だけ呼び出しを繰り返すためです。
また、これは元の実装と外延的に等価ではありません。元の
MOD
のバージョンは
ZERO
で割ろうとする
と永久にループしますが（条件
n <= m
は決して偽にならないため）、こちらの実装では第1引数を返し
ます。
>>
to_integer(MOD[THREE][ZERO])
=> 3
RANGE
はもう少し厄介になりますが、
DECREMENT
でやったのと同じテクニックが使えます。最初
の引数で
n
回呼び出されると、求める範囲から
n
個のリストを返す、という関数を設計します。
DECREMENT
と同じように、ペアを使うことによって、結果としてのリストと次のイテレーションに必
要な情報の両方を格納するところがコツになります。
def countdown(pair)
[pair.first.unshift(pair.last), pair.last - 1]
end
>>
countdown([[], ...
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.