多段階選抜 (Lua)


|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|

<del>cbrtはlmathxパッケージを使用しています。</del>不要になりました。

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

-- require 'mathx' -- luarocks install lmathx

function isqrt(n)
	if n<=0 then
		return 0
	end
	if n<4 then
		return 1
	end
	local x=0
	local y=n
	while x~=y and x+1~=y do
		x=y
		y=(n//y+y)//2
	end
	return x
end
function icbrt(n)
	if n<0 then
		return -icbrt(-n)
	end
	if n==0 then
		return 0
	end
	if n<8 then
		return 1
	end
	local x=0
	local y=n
	while x~=y and x+1~=y do
		x=y
		y=(n//y//y+y*2)//3
	end
	return x
end

function generate()
	return coroutine.create(function()
		local i=1
		while true do
			coroutine.yield(i)
			i=i+1
		end
	end)
end
function drop_prev(check,prev)
	return coroutine.create(function()
		local a,b
		_,a=coroutine.resume(prev)
		_,b=coroutine.resume(prev)
		while true do
			if not check(b) then
				coroutine.yield(a)
			end
			a=b
			_,b=coroutine.resume(prev)
		end
	end)
end
function drop_next(check,prev)
	return coroutine.create(function()
		local a,b
		_,a=coroutine.resume(prev)
		_,b=coroutine.resume(prev)
		coroutine.yield(a)
		while true do
			if not check(a) then
				coroutine.yield(b)
			end
			a=b
			_,b=coroutine.resume(prev)
		end
	end)
end
function drop_n(check,n,prev)
	return coroutine.create(function()
		local i=0,a
		while true do
			i=i+1
			_,a=coroutine.resume(prev)
			if not check(i,n) then
				coroutine.yield(a)
			end
		end
	end)
end

function is_sq(n)
	-- local x=math.floor(math.sqrt(n))
	local x=isqrt(n)
	return x*x==n
end
function is_cb(n)
	-- local x=math.floor(math.cbrt(n))
	local x=icbrt(n)
	return x*x*x==n
end
function is_multiple(i,n)
	return i%n==0
end
function is_le(i,n)
	return i<=n
end

local f={
	['S']=function(e) return drop_next(is_sq,e) end,
	['s']=function(e) return drop_prev(is_sq,e) end,
	['C']=function(e) return drop_next(is_cb,e) end,
	['c']=function(e) return drop_prev(is_cb,e) end,
	['h']=function(e) return drop_n(is_le,100,e) end,
}
local i,r
for i=2,9 do
	f[tostring(i)]=function(e) return drop_n(is_multiple,i,e) end
end
local line=io.read('*line')
while line~=nil do
	local g=generate()
	for c in line:gmatch('.') do
		g=f[c](g)
	end
	for i=1,10 do
		if i>1 then
			io.write(',')
		end
		_,r=coroutine.resume(g)
		io.write(r)
	end
	io.write("\n")
	io.flush()
	line=io.read('*line')
end
```