關於 the swap ，我們在網路上蒐集到這些相關的討論、資訊與評價

Mr. and Mrs. S̶m̶i̶ - Ho 😎 That's rightttt! If you're into Nerf, then you already know the behemoth of a blaster Mrs. Ho is carrying: The new Nerf Ultra Select. It has 2 clips so you can swap between distance or accuracy with the Nerf Ultra darts. BOOM! 💥

If you're the type that is scared of your wife like me, then get acquainted with the Nerf Elite 2.0 Phoenix CS6, by no means a blaster you should be underestimating! It’s an upgrade ready, motorized blaster with 5 tactical rails, stock & barrel attachment points, 6 dart-clip and my favourite part, a removable scope so you NEVER miss! It’s Nerf or Nothin’! 😉

@HasbroMY @shopee_my
#NERFActivePlay #NerfMY

📜 [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

Joined the Prezitt x LoveXpress Foundation Launch Party on today at Lee Tung Street.

The Prezitt apps is very functional. It can help you to send a gift to your friends everywhere and explore the gift ideas. Also discover events in different cities.

Recently, the Prezitt app has launched the new function - “Wish List & Recommendations”, “Send Swap Receive” and “Donation”.

Let’s download the Prezitt app and enjoy your happy moment with it😉

Thank you for having me Prezitt LoveXpress 愛傳遞 🥰♥️

#prezitt #lovexpresshk #charity #charityevent #asianbeauty #photograph #pretty #model #hkmodel #vsco #portraits_ig #hk_portrait #flimphotography #blogger #hkblogger #lifestyleblogger #lifestyle #traveller #travelblogger #travelphotography #fashion #fashionblogger #love #kol

概要欄です。
皆さんはママの10代向けのファッションいかがだったでしょうか？

0:00 | 挨拶
0:41 | ドッキリの説明
2:04 | 作戦会議
2:47 | お着替えタイム
3:52 | チェンジ後
4:42 | ドッキリスタート
7:52 | HAYAの感想
8:41 | 色々アウトです
9:08 | 予告
9:30 | 反省会


【自己紹介】
あや（AYA)、はや（HAYA）、かの（KANO)の女男女の3人姉兄妹と、その家族の日常の様子を動画にしています。
是非チャンネル登録をお願いします。メインチャンネルとなっています。

あやはやチャンネルのページ（このチャンネルですよ）
https://www.youtube.com/channel/UCtmX0fdBSiKUpVI2daVRHhA?sub_confirmation=1

サブチャンネルのページ
https://www.youtube.com/channel/UC2EeMH7b-QdckszKqD_T5Dw?sub_confirmation=1

あやはや家ゲームのページ
https://www.youtube.com/channel/UCAr7lugAlzGF2wTA1egu2Kw?sub_confirmation=1

♥あやはやのTwitterが出来ました！新しい動画が公開されるといち早くわかりますよ。
https://twitter.com/AyahayaC
Instagram
https://www.instagram.com/ayahayac/
Tiktok
https://www.tiktok.com/@ayahayac


【こちらも】
周りの空気が読むのが苦手な子に見られる特徴とその解決方法
https://youtu.be/llAZoY9za0E

【やっぱり怖い】12歳の子に届いたウイルスワクチン接種の案内！前回の動画でたくさんのコメントありがとうございます
https://youtu.be/2XV_jY1MDbY

夏休みゲームやり放題をかけて！ボール投げチャレンジに挑戦！まさに夢のような企画？どん底へ
https://youtu.be/8yPDndP04eI

12歳の子にもコロナワクチン接種券が届きました！でも肝心のあの予防接種が打てない現状！
https://youtu.be/CqZL-uVxFAU

千円で30分好きなもの買い放題！と思って来たのに実際は500円！上手にお買い物できるのか！
https://youtu.be/vTFEfc4lR4A


■学校・生活の再生リスト
https://www.youtube.com/playlist?list=PLRJ5499dWynkpwrjSeiJNOiNC--blYo1g


■お問い合わせは
チャンネルの概要欄をご確認ください
https://www.youtube.com/channel/UCtmX0fdBSiKUpVI2daVRHhA/about

◆BGM使わせて頂いております
http://musmus.main.jp/
https://the-arcadium.net/
甘茶の音楽工房：http://amachamusic.chagasi.com/
Music by Tobu　http://www.youtube.com/tobuofficial


 
*********************
*　見てくれてありがとう  *
*********************

#服装チェンジ
#ドッキリ
＃入れ替り
#あやはや
#familyfun

#Clothingchange
#Candidcamera
#Swap

Whether you’re preparing specifically for Second Hand September or are hoping to add more secondhand finds to your closet in general, online thrifting apps and websites are some of the most convenient ways to purchase secondhand garments at the moment. This is the ultimate guide to online thrift stores covers the pros and cons of 13 different online secondhand fashion retailers in the US.

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Connect for more on sustainable fashion and conscious living:
https://www.instagram.com/thesensiblefay
https://thesensiblefay.com/

Support me on Ko-Fi:
https://ko-fi.com/thesensiblefay

-----------------------------------------------------------------------------------------------------------------------
Timestamps:
Intro: 0:00 - 0:22
ThredUp: 0:22 - 2:53
Poshmark: 2:53 - 4:48
Depop: 4:48 - 5:50
Ebay: 5:50 - 7:02
Patagonia Worn Wear: 7:02 - 8:32
Facebook Marketplace: 8:32 - 10:12
Etsy: 10:12 - 11:36
Mercari: 11:36 - 13:00
Tradesy: 13:00 - 14:06
Ruby Lane: 14:06 - 15:50
Bonanza: 15:50 - 17:00
Swap: 17:00 - 18:18
Vestiaire Collective: 18:18 - 19:45
Conclusion: 19:45 - 20:24

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*Music:*
✨ Andreas Owens - falling & falling - https://thmatc.co/?l=F499146A
✨ Linanthem - moonlight - https://thmatc.co/?l=179E9133
✨ Naomi - Osaka - https://thmatc.co/?l=A889BD5E
✨ Naomi - Remember me? - https://thmatc.co/?l=76068690
✨ Naomi - Departure - https://thmatc.co/?l=6C9D7B99
✨ Naomi - Our Story - https://thmatc.co/?l=12680AAE
✨ Naomi - If Love is the Answer - https://thmatc.co/?l=74F2F967

#美國家庭#台灣生活#Taiwan

🎈莎白的Instagram日常: https://www.instagram.com/elizabenny/?hl=en
🎈莎白的Facebook專頁: https://m.facebook.com/shabaianderic/
🎈合作邀約請洽(Business inquiries):elizabeth@pressplay.cc