多段階選抜 (Ruby Ractor)


|多段階選抜|解答日|シリーズ:yieldの練習/ジェネレータを入れ子に/整数平方根・立方根の実装|
|:--|:--|:--|
|問題|　|http://nabetani.sakura.ne.jp/hena/ord24eliseq/<br>https://qiita.com/Nabetani/items/1c83005a854d2c6cbb69|
|Ruby|2014/8/2(当日)|https://qiita.com/cielavenir/items/9f15e29b73ecf98968a5|
|C#/Python|2014/8/4|https://qiita.com/cielavenir/items/a1156e6a4f71ddbe5dcb|
| |　|ここから上はdrop_prev_square/drop_prev_cubicをまとめる前の答案|
|Go/C#/Ruby/Python|2014/8/5|https://qiita.com/cielavenir/items/2a685d3080862f2c2c47|
|PHP/JavaScript|2014/9/9|https://qiita.com/cielavenir/items/28d613ac3823afbf8407|
|VB|2014/9/10|https://qiita.com/cielavenir/items/cb7266abd30eadd71c04|
|D|2015/12/21|https://qiita.com/cielavenir/items/47c9e50ee60bef2847ec|
|Perl|2017/3/10|https://qiita.com/cielavenir/items/6dfbff749d833c0fd423|
|Lua|2017/3/13|https://qiita.com/cielavenir/items/c60fe7e8da73487ba062|
|C++20(TS)|2017/3/15|https://qiita.com/cielavenir/items/e1129ca185008f49cbab (MSVC)<br>https://qiita.com/cielavenir/items/1cfa90d73d11bb7dc3d4 (clang)|
|F#|2017/3/17|https://qiita.com/cielavenir/items/a698d6a26824ff53de81|
|Boo/Nemerle|2017/5/13|https://qiita.com/cielavenir/items/e2a783f0fe4b0fe0ed48|
|Perl6|2017/5/15|https://qiita.com/cielavenir/items/656ea17fa96c865c4498|
|Kotlin|2017/5/25|https://qiita.com/cielavenir/items/9c46ce8d9d12e51de285|
|Crystal|2018/5/8|https://qiita.com/cielavenir/items/1815bfa6a860fd1f90db|
|MoonScript|2018/6/16|https://qiita.com/cielavenir/items/8b03cce0386f4537b5ad|
|Julia/Rust|2018/12/20|https://qiita.com/cielavenir/items/3ddf72b06d625da0c4a5|
|Nim|2018/12/26|https://qiita.com/cielavenir/items/5728944867e609fd52a7|
|Tcl|2018/12/31|https://qiita.com/cielavenir/items/76cbd9c2022b48c9a2c9|
|Pascal/Cobra|2019/1/16|https://qiita.com/cielavenir/items/81b81baf8dfc1f877903|
|Icon|2019/1/17|https://qiita.com/cielavenir/items/889622dcc721f5a4da24|
|Swift|2020/5/31|https://qiita.com/cielavenir/items/3b0b84a218e35d538f7f|
|Java/Groovy/Scala|2020/5/31|https://qiita.com/cielavenir/items/7f058203a8fd03b65870|
|V|2020/10/17|https://qiita.com/cielavenir/items/df30a6c101a97a713df5|
|Zig/Zen|2020/10/17|https://qiita.com/cielavenir/items/9cced9e4a94dcd70df0f|
|Pike|2020/11/2|https://qiita.com/cielavenir/items/3a8248f41611302b34fd|
|Vala/Smalltalk|2020/11/29|https://qiita.com/cielavenir/items/085dabe593cd916af5e8|
|Objective-C|2020/11/30|https://qiita.com/cielavenir/items/a1736e38789a3dd5cc5a|
|Ruby(Ractor)|2021/1/2|https://qiita.com/cielavenir/items/f493c6d512b63cc571cc|
|Python(_xxsubinterpreters)|2021/6/29|https://qiita.com/cielavenir/items/f1f581a055db918954f1|
|Falcon/Scheme|2021/9/5|https://qiita.com/cielavenir/items/c13d12cf44f0d17f4a94|
|Clojure/Lisp|2021/9/7|https://qiita.com/cielavenir/items/7458ba076f4e5bc0f196|
|(icbrtの実装に関する)補題|2017/5/11|整数除算であってもn/(x*y)はn/x/yに等しい(ことの証明)<br>https://qiita.com/cielavenir/items/21a6711afd6be8c18c55|

新年早々(笑[^1])

- Procってsharableでないんですね。。破壊的変更ってできましたっけ。
- `Proc#[]`は使わないようにしました。`.()`は`#call`の[糖衣構文](https://qiita.com/tbpgr/items/71a2bac3ec53277387d8)(`#call`メソッドを持つ全てのオブジェクトに通用する)です。


```rb
#!/usr/bin/env ruby
#http://qiita.com/Nabetani/items/1c83005a854d2c6cbb69
#http://nabetani.sakura.ne.jp/hena/ord24eliseq/

raise 'Ractor is not available (CRuby 3.0+ implements it). There is also non_ractor version.' if !defined?(Ractor)

class Integer
	def isqrt
		return 0 if self<=0
		return 1 if self<4 # 1
		x,y=0,self
		while x!=y&&x+1!=y
			x,y=y,(self/y+y)/2
		end
		x
	end
	def icbrt
		return -(-self).icbrt if self<0
		return 0 if self==0
		return 1 if self<8 # 1,7
		x,y=0,self
		while x!=y&&x+1!=y
			x,y=y,(self/y/y+y*2)/3
		end
		x
	end
end

def generate
	Ractor.new{
		i=1
		loop{
			Ractor.yield i
			i+=1
		}
	}
end

def drop_prev(check,prev)
	Ractor.new(check,prev){|check,prev|
		a=nil
		b=prev.take
		loop{
			a,b=b,prev.take
			Ractor.yield a if !check.(b)
		}
	}
end
def drop_next(check,prev)
	Ractor.new(check,prev){|check,prev|
		first=true
		a=nil
		b=nil
		loop{
			a,b=b,prev.take
			(first=false;Ractor.yield b) if (first || !check.(a))
		}
	}
end
def drop_n(check,n,prev)
	Ractor.new(check,n,prev){|check,n,prev|
		i=0
		loop{
			i+=1
			a=prev.take
			Ractor.yield a if !check.(i,n)
		}
	}
end

is_sq = Ractor.make_shareable ->n{n.isqrt**2==n}
is_cb = Ractor.make_shareable ->n{n.icbrt**3==n}
is_multiple = Ractor.make_shareable ->i,n{i%n==0}
is_le = Ractor.make_shareable ->i,n{i<=n}

f={
	'S'=>Kernel.method(:drop_next).to_proc.curry.(is_sq),
	's'=>Kernel.method(:drop_prev).to_proc.curry.(is_sq),
	'C'=>Kernel.method(:drop_next).to_proc.curry.(is_cb),
	'c'=>Kernel.method(:drop_prev).to_proc.curry.(is_cb),
	'h'=>Kernel.method(:drop_n).to_proc.curry.(is_le,100),
}
(2..9).each{|e|f[e.to_s]=Kernel.method(:drop_n).to_proc.curry.(is_multiple,e)}

if $0==__FILE__
	STDOUT.sync=true
	while gets
		x = $_.chomp.chars.reduce(generate){|s,e|f[e].(s)}
		puts 10.times.map{x.take}*','
	end
end
```

[^1]: 論文をやれ