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Any luck with winning at least NT$200 this time? A total of four uniform invoices issued in July and August had the winning serial number drawn Saturday in the bimonthly lottery draw for the top prize of NT$10 million (US$359,912).
https://focustaiwan.tw/business/202109260007
📜 [專欄新文章] Gas Efficient Card Drawing in Solidity
✍️ Ping Chen
📥 歡迎投稿： https://medium.com/taipei-ethereum-meetup #徵技術分享文 #使用心得 #教學文 #medium
Assign random numbers as the index of newly minted NFTs
Scenario
The fun of generative art NFT projects depends on randomness. The industry standard is “blind box”, where both the images’ serial number and the NFTs’ index are predetermined but will be shifted randomly when the selling period ends. (They call it “reveal”) This approach effectively solves the randomness issue. However, it also requires buyers to wait until the campaign terminates. What if buyers want to know the exact card right away? We’ll need a reliable onchain card drawing solution.
The creator of Astrogator🐊 isn’t a fan of blind boxes; instead, it thinks unpacking cards right after purchase is more interesting.
Spec
When initializing this NFT contract, the creator will determine the total supply of it. And there will be an iterable function that is randomly picking a number from the remaining pool. The number must be in range and must not collide with any existing ones.
Our top priority is accessibility/gas efficiency. Given that gas cost on Ethereum is damn high nowadays, we need an elegant algorithm to control gas expanse at an acceptable range.
Achieving robust randomness isn’t the primary goal here. We assume there’s no strong financial incentive to cheat, so the RNG isn’t specified. Implementers can bring their own source of randomness that they think is good enough.
Implementation
Overview
The implementation is pretty short and straightforward. Imagine there’s an array that contains all remaining(unsold) cards. When drawIndex() is called, it generates a (uniform) random seed to draw a card from the array, shortens the array, and returns the selected card.
Algorithm
Drawing X cards from a deck with the same X amount of cards is equal to shuffling the deck and dealing them sequentially. It’s not a surprise that our algorithm is similar to random shuffling, and the only difference is turning that classic algo into an interactive version.
A typical random shuffle looks like this: for an array with N elements, you randomly pick a number i in (0,N), swap array[0] and array[i], then choose another number i in (1,N), swap array[1] and array[i], and so on. Eventually, you’ll get a mathematically random array in O(N) time.
So, the concept of our random card dealing is the same. When a user mints a new card, the smart contract picks a number in the array as NFT index, then grabs a number from the tail to fill the vacancy, in order to keep the array continuous.
Tweak
Furthermore, as long as the space of the NFT index is known, we don’t need to declare/initialize an array(which is super gas-intensive). Instead, assume there’s such an array that the n-th element is n, we don’t actually initialize it (so it is an array only contains “0”) until the rule is broken.
For the convenience of explanation, let’s call that mapping cache. If cache[i] is empty, it should be interpreted as i instead of 0. On the other hand, when a number is chosen and used, we’ll need to fill it up with another unused number. An intuitive method is to pick a number from the end of the array, since the length of the array is going to decrease by 1.
By doing so, the gas cost in the worst-case scenario is bound to be constant.
Performance and limitation
Comparing with the normal ascending index NFT minting, our random NFT implementation requires two extra SSTORE and one extra SLOAD, which cost 12600 ~ 27600 (5000+20000+2600) excess gas per token minted.
Theoretically, any instantly generated onchain random number is vulnerable. We can restrict contract interaction to mitigate risk. The mitigation is far from perfect, but it is the tradeoff that we have to accept.
ping.eth
Gas Efficient Card Drawing in Solidity was originally published in Taipei Ethereum Meetup on Medium, where people are continuing the conversation by highlighting and responding to this story.
👏 歡迎轉載分享鼓掌
Taiwan needs to face the issue of a decade-long ban on Japanese food imports from areas affected by the 2011 nuclear disaster, now that it has formally applied to join the Tokyo-led #CPTPP, the nation's top trade negotiator said on Thursday.
https://focustaiwan.tw/politics/202109230005
Listen to the single "NOT A CYPHER". Out now!
Stream: https://music.empi.re/notacypher.oyd
NOT A CYPHER
-----------------------------------------------------------
MV PRESENTED BY:
Mercy Creatives 美杰創意影像工作室
Spotlight X
SHFT
theLOOP
Murphy
Directors | Drew Cheng / Kelvin Lee
Producer | Greg Cheng
Editor | Richard Yang
—Taipei Unit—
Director | Drew Cheng / Kelvin Lee
Producer | Greg Cheng
Director of Photography | Richard Yang
First AC | Ashley Yang
Associate Producer | Keen Chen / Megan Peng
Production Assistant | Christine Lin / Kendra Ing / Cavin Fang / Adrian Town / Francis Yu / Jessica Yu
Art Director | Megan Peng
Associate Art Producer | Richard Yang
Stylist | Meishin
Stylist Assistant | Cindy Chao
Hair | Martha Wu
Makeup Artist | Albee Hsieh / Backstage
Makeup Artist Assistant | Doris Zheng / Backstage
A&R Managers | DJ bo / WL46
—Shanghai Unit—
Director | Dill
Producer | SK
Director of Photography | Vann Lee
Production Assistant | Qiuyang Guo / Yao Yan / Chengqiang Wu / Psr
—Special Thanks—
Charlene Yang, Chunplace / Hotel Indigo Taipei North
Alchelight
Laticia Fan, f/Lash Productions
Bar Rouge Shanghai
-----------------------------------------------------------
LYRICS:
《INTRO》
BLOW:
yeh bless it
i dont wanna fuck unless she nasty
yeh bring her bestie
ima hit em both if she let me enh
太热需要pepsi enh
不能说太多thats it enh
cant test me enh
《Verse 1》
SHADOW PROJECT:
[Ye!!ow]
(What’s your color)
聽到我的聲音腦袋快開機
四面楚歌快點充滿你的 Energy
看到影子低空掠過正在飆的戰鬥機
要我飛的更高需要看到更多 Enemy
(that’s cool)
不停的轟炸雷達warning
下一個舞台我把眼光放在國際
SP we gang gang繼續追我倒影
飆高速列車 Skrr Skrr Skrr Skrr
Ya u Better go get em
[Paper Jim]
(Counting Papers)
Go get them
風格唯一我們前面沒有別人
說一就是一 二就是二
付錢看表演我是主人你們是客
Shut your mouth 不說閒話沒人嫌你吵
我有我的心魔在音樂不講禮貌
槍口一致朝外Pow we gone
Sp we gone bust it down
[Bu$Y]
你無法猜透的劇情
踏上更大的場面 No limit
不斷攀升身價不用你評比
Want me to show up 之前得要先 Pay me
Overheat and blow it up
Used to talking shit around me now we growin up
別在我兄弟面前表現得不禮貌
You can see me on the stage and we gon pull it up
BLOW:
(Can’t test me!)
《Verse 2》
XZT of 直火幫:
Verse 2, XZT玩弄你肾上腺素
直火帮名字在逐渐遍布
保守点说 中文说唱前五
他让我follow the wave
让我为资本低头 我偏不
垃圾们组成的队伍
废物到最后也只会是废物
今年是直火年 丰收的果园 我们经历过火焰般 严苛的磨炼
我进度不拖延 目光从不会放在昨天 你不懂 我看得有多远
hater们咽下了唾液
失败的对手像落叶
wordplay and flow like toys
new chiggas不停地落泪
注视King XZT不会退缩的眼睛
Get shit done 无关对错的原因
看着我兄弟们就像在点兵
SFG a dragon 我就像在点睛
Life’s a battle 我拳头在变硬
没去过ghetto 但我一字千金
做你的idol 我拍我的电影
当我开口 你问我要签名
BLOW:
当我开口你问我要签名
风格鲜明
下雨天晴 当我工作你喝到天明
slow down i got my style i got my shit
花招 thats not shit
拔我插销我对你发泄
像花椒加上hot suace
让你流汗或者pass out
我看灯光都是线条
still link the the gang像链条⛓️
不是儿童歌 heheh
不是儿童歌这是rap yo
那些坏料总是带笑
listen up 为你害臊
我需要一些good friends不在背后talk shit
需要一些mula像十月份的落叶
需要一些real one不用一直攻受
还需要个bad chick 但我已经拥有
《Outro》
BLOW:
weird 电闪
im black like batman
看上海City慢慢变暗
让我干掉他们就像吃便饭
switch switch 看我一直变换
mfk 2 face that one
riding around the city my shiton top
cuz im walk 看他们只是talk
-----------------------------------------------------------
Follow KING CHAIN
http://facebook.com/kingchainmusic
http://instagram.com/kingchainmusic
http://soundcloud.com/kingchainmusic
http://twitter.com/kingchainmusic
Follow 影子計畫 Shadow Project
http://facebook.com/shadowunlock
http://instagram.com/shadow__project__/
Follow Blow Fever
http://facebook.com/blowfever
https://www.instagram.com/blowfever/
https://www.youtube.com/channel/UCAHzdOH5p7kh9FYnR-xXbiA
Follow 直火幫 XZT
http://instagram.com/sfgxzt
https://www.youtube.com/channel/UCpavtVoUxKSOg7C7HYc6A2A
https://weibo.com/u/2140141403
Follow Mercy Creatives
http://facebook.com/mercycreatives
http://instagram.com/mercycreatives
#KINGCHAIN #BlowFever #ShadowProject #XZT
Official video by KING CHAIN ft. Blow Fever, Shadow Project & XZT - NOT A CYPHER © 2021 NIGHT SHFT / EMPIRE / KINGCHAIN
🔺【2021台灣年度風雲車】 👉 https://pse.is/38y4a5
🔺【Go車誌 App 下載連結】👇👇👇
iOS系統：https://pse.is/3klzd8
Android系統：https://pse.is/3llbzc
--------------------------------------------------------
更多影片盡在Go車誌官網：https://www.buycartv.com/
Till I Know What Love Is(I'm Never Gonna Die) from AIMYON TOUR 2021“FELL in LOVE with the WOUND & the DEVIL”.
AIMYON TOUR 2021“FELL in LOVE with the WOUND & the DEVIL”
May 12 Asahikawa civic culture hall ,HOKKAIDO
May 14 Obihiro civic culture hall ,HOKKAIDO
May 23 Yonago convention center-BiG SHiP- ,TOTORI
May 27 Kochi prefectural culture hall-Orange- ,KOCHI
Jun 2 Yokkaichi city cultural center-1- ,MIE
Jun 4 Hamamatsu-Act city- ,SHIZUOKA
Jun 11 Saga civic culture hall-Large- ,SAGA
Jun 12 Kawasho hall(Kagoshima civic culture hall-1-) ,KAGOSHIMA
Jun 23 Hokuto culture hall(Nagano prefectural culture hall-Large-) ,NAGANO
Jun 26 Kawaguchiko stellar theater ,YAMANASHI
Jul 1 Iwate prefectural hall ,IWATE
Jul 11 Utsunomiya city cultural hall ,TOCHIGI
Jul 15 Rohm theatre Kyoto-Main- ,KYOTO
Jul 16 Osaka castle band shell ,OSAKA
Aug 2 Festival hall ,OSAKA
＝＝＝＝＝＝＝＝＝＝＝
AIMYON：
Genuine & authentic are the perfect words to describe Aimyon, a guitar-strumming storyteller of today’s youth in Japan.
Without a doubt she is one of the biggest artists in the Japanese music scene. She has fans around the world and those in Taipei and Shanghai were lucky enough to see her perform live in their cities.
She has had constant hits including “Naked Heart”, “Let the Night” (each with 100 million streams certified by Billboard) and “Marigold” (first ever Japanese song to hit 100 million streams, and racking up 200 million streams to date) to name a few. She is one of the first artists in Japan to truly flourish through streaming platforms where young music listeners come to discover new music. Fans are always looking out for the visual sides of Aimyon as well: Her music videos are never over the top but entertaining, real and soothing. Aimyon’s favorite artwork designer Tondabayashi Ran also knows how to add Aimyon flavor to each release, helping to create her distinct world.
Official YouTube
https://youtube.com/user/aimyong
Official Twitter
https://twitter.com/aimyongtter
Official Instagram
https://www.instagram.com/aimyon36/
Official Weibo
https://weibo.com/u/7099412531
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