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/
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)
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

(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)
https://qiita.com/cielavenir/items/21a6711afd6be8c18c55

Generator::Objectモジュールを使用。


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);
}