多段階選抜 (Perl)


|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|

Generator::Objectモジュールを使用。

```pl:tyama_hena24_enum.pl
#!/usr/bin/env perl
#http://qiita.com/Nabetani/items/1c83005a854d2c6cbb69
#http://nabetani.sakura.ne.jp/hena/ord24eliseq/

use strict vars;
use feature qw(say);
use IO::Handle;
use Generator::Object;
use List::Util qw(reduce);

#sub cbrt{
#	my($n)=@_;
#	return $n**(1-2.0/3);
#}

sub isqrt{
	my($n)=@_;
	if($n<=0){return 0;}
	if($n<4){return 1;}
	my $x=0;my $y=$n;
	for(;$x!=$y&&$x+1!=$y;){$x=$y;$y=int((int($n/$y)+$y)/2);}
	return $x;
}
sub icbrt{
	my($n)=@_;
	if($n<0){return -icbrt(-$n);}
	if($n==0){return 0;}
	if($n<8){return 1;}
	my $x=0;my $y=$n;
	for(;$x!=$y&&$x+1!=$y;){$x=$y;$y=int( (int(int($n/$y)/$y)+$y*2)/3 );}
	return $x;
}

sub generate{
	generator{
		my $i=1;
		for(;;){
			$_->yield($i);
			$i++;
		}
	}
}

sub drop_prev{
	my($check,$prev)=@_;
	generator{
		my $a=$prev->next;
		my $b=$prev->next;
		for(;;){
			$_->yield($a) if !$check->($b);
			$a=$b;
			$b=$prev->next;
		}
	}
}
sub drop_next{
	my($check,$prev)=@_;
	generator{
		my $a=$prev->next;
		my $b=$prev->next;
		$_->yield($a);
		for(;;){
			$_->yield($b) if !$check->($a);
			$a=$b;
			$b=$prev->next;
		}
	}
}
sub drop_n{
	my($check,$n,$prev)=@_;
	generator{
		my $i=0;
		for(;;){
			$i+=1;
			$a=$prev->next;
			$_->yield($a) if !$check->($i,$n);
		}
	}
}
sub is_sq{
	my($n)=@_;
	#my $x=int(sqrt($n));
	my $x=isqrt($n);
	return $x*$x==$n;
}
sub is_cb{
	my($n)=@_;
	#my $x=int(cbrt($n));
	my $x=icbrt($n);
	return $x*$x*$x==$n;
}
sub is_multiple{
	my($i,$n)=@_;
	return $i%$n==0;
}
sub is_le{
	my($i,$n)=@_;
	return $i<=$n;
}

my %f=(
	'S'=>sub{my($enum)=@_;return drop_next('is_sq',$enum);},
	's'=>sub{my($enum)=@_;return drop_prev('is_sq',$enum);},
	'C'=>sub{my($enum)=@_;return drop_next('is_cb',$enum);},
	'c'=>sub{my($enum)=@_;return drop_prev('is_cb',$enum);},
	'h'=>sub{my($enum)=@_;return drop_n('is_le',100,$enum);},
);
for(my $i=2;$i<=9;$i++){$f{"$i"}=sub{my($i)=@_;sub{my($enum)=@_;return drop_n('is_multiple',$i,$enum);}}->($i);}

STDOUT->autoflush;
for(;my $line=<>;){
	chomp($line);
	#cS => $f['S']->($f['c']->(generate()))
	my $z=reduce {$f{$b}->($a)} generate(),split('',$line);
	my $cnt=10;
	my @a;
	for(my $i=0;$i<$cnt;$i++){
		push(@a,$z->next);
	}
	say join(',',@a);
}
```