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多段階選抜 (VB)

Last updated at Posted at 2014-09-10
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
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)
https://qiita.com/cielavenir/items/21a6711afd6be8c18c55

VB

うまくテストできなかったので、WinでコンパイルしたexeをOSXに転送してテストした。
なので細かい部分が怪しいですが、気にしない。
ちなみにWinで直接実行した限りでは、DllImportは msvcr120 にしないといけなかった。びっくり。

hena24_enum.vb
' http://qiita.com/Nabetani/items/1c83005a854d2c6cbb69
' http://nabetani.sakura.ne.jp/hena/ord24eliseq/

imports System
imports System.Linq
imports System.Collections.Generic
'imports System.Runtime.InteropServices

module Hena24
    '<DllImport("c")>
    'private function cbrt(ByVal d as double) as double
    'end function

    private function isqrt(ByVal n as integer) as integer
        if n<=0
            return 0
        end if
        if n<4
            return 1
        end if
        dim x as integer=0
        dim y as integer=n
        while x<>y andalso x+1<>y
            x=y
            y=((n\y)+y)\2
        end while
        return x
    end function
    private function icbrt(ByVal n as integer) as integer
        if n<0
            return -icbrt(-n)
        end if
        if n=0
            return 0
        end if
        if n<8
            return 1
        end if
        dim x as integer=0
        dim y as integer=n
        while x<>y andalso x+1<>y
            x=y
            y=((n\y\y)+y*2)\3
        end while
        return x
    end function

    private function is_sq(ByVal n as integer) as boolean
        dim x as integer=isqrt(n)
        'cint(Math.Sqrt(n))
        return x*x=n
    end function

    private function is_cb(ByVal n as integer) as boolean
        dim x as integer=icbrt(n)
        'cint(cbrt(n))
        return x*x*x=n
    end function

    private function is_multiple(ByVal i as integer,ByVal n as integer) as boolean
        return i mod n=0
    end function
    private function is_le(ByVal i as integer,ByVal n as integer) as boolean
        return i<=n
    end function

    iterator function generate() as IEnumerable(of integer)
        dim i as integer=1
        while true
            yield i
            i+=1
        end while
    end function

    iterator function drop_prev(ByVal check as Func(of integer,boolean),ByVal _prev as IEnumerable(of integer)) as IEnumerable(of integer)
        dim prev as IEnumerator(of integer)=_prev.GetEnumerator()
        prev.MoveNext()
        dim a as integer=prev.Current
        prev.MoveNext()
        dim b as integer=prev.Current
        while true
            if not check(b)
                yield a
            end if
            a=b
            prev.MoveNext()
            b=prev.Current
        end while
    end function

    iterator function drop_next(ByVal check as Func(of integer,boolean),ByVal _prev as IEnumerable(of integer)) as IEnumerable(of integer)
        dim prev as IEnumerator(of integer)=_prev.GetEnumerator()
        prev.MoveNext()
        dim a as integer=prev.Current
        prev.MoveNext()
        dim b as integer=prev.Current
        yield a
        while true
            if not check(a)
                yield b
            end if
            a=b
            prev.MoveNext()
            b=prev.Current
        end while
    end function

    iterator function drop_n(ByVal check as Func(of integer,integer,boolean),ByVal n as integer,ByVal _prev as IEnumerable(of integer)) as IEnumerable(of integer)
        dim prev as IEnumerator(of integer)=_prev.GetEnumerator()
        dim i as integer=0
        while true
            i+=1
            prev.MoveNext()
            dim a as integer=prev.Current
            if not check(i,n)
                yield a
            end if
        end while
    end function

    sub Main()
        dim f as new Dictionary(of char,Func(of IEnumerable(of integer),IEnumerable(of integer))) from {
            {"S"c,Function(e) drop_next(addressof is_sq,e)},
            {"s"c,Function(e) drop_prev(addressof is_sq,e)},
            {"C"c,Function(e) drop_next(addressof is_cb,e)},
            {"c"c,Function(e) drop_prev(addressof is_cb,e)},
            {"h"c,Function(e) drop_n(addressof is_le,100,e)}
        }
        for i as integer=2 to 9
            dim j as integer=i
            f(chr(48+j)) = Function(e) drop_n(addressof is_multiple,j,e)
        next
        dim line as string=Console.ReadLine()
        while line isnot nothing
            dim first as boolean=true
            'cS => f("S"c)(f("c"c)(generate()))
            for each n as integer in line.Aggregate(generate(),Function(s,e) f(e)(s)).Take(10)
                if not first
                    Console.Write(","c)
                end if
                first=false
                Console.Write(n)
            next
            Console.WriteLine()
            Console.Out.Flush()
            line=Console.ReadLine()
        end while
    end sub
end module
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