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Utilizing sweeping motions, @lavieaestheticssg Super Hair Removal (SHR) covers more areas - FASTER 💨 More efficient, effective and comfortable than Intense Pulse Light (IPL), it concentrates on fine hairs as well as coarse. In my ninth session now, I see slower regrowth on larger area.
Follow my journey on igstories highlight titled ‘SHR’ and #linkinbio 🧚🏿 linkin.bio/janiqueel
📜 [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
🔰TJs ⚠️ Which one should I side?
Here are the most efficient way of getting into TJs.
I will share which side to you knee you lifted, and which type of side swing.
1️⃣Crougar - Opposite Side Swing, Cross Side Swing - Apply to Johnny too
2️⃣Toad - Same Side Swing, Open Side Swing
3️⃣Inverse Toad, Opposite Side Swing, Open Side Swing
4️⃣Elephant - Same Side Swing, Cross Side Swing
Hope this will sort out your confusion😜
It is good for beginner to start with more efficient way to progress too
Try!!!
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公司簡介
歐美國家的物業與居家服務產業需要能管理臨時人員進出，樂邦安控看到現有門禁和房產服務應該做更有效地結合，將門禁管理透過4G/5G連上雲端，提供更完整的權限管理以及連結相關房產服務，以因應日益增多的物業管理及居家服務自動化需求。整體解決方案包含硬體、管理軟體及雲端平台三要件。硬體解決方案為電子化鑰匙盒，其重要的環節是身份驗證，樂邦安控使用的動態二維碼識別已在美國申請專利，透過這樣的驗證方式，不只安全度提升、免除許多物業管理雜務，更有助於串連各項物業管理服務與居家服務，同時達到服務創新的目的。
At Lubn, we are enabling data-driven property management through an integrated hardware & software platform.
Did you know there were 138M properties in the US and near half of them were being managed by realtors or property managers last year? Yes, we want to help Property Manager’s and Realtors become more efficient at managing the properties. We developed an intelligent property management platform by integrating hardware, software and services. The hardware is an LTE connected smart key box with an embedded camera. The device collects the data with its embedded sensors and sends to Lubn Dashboard where we can provide Managers business intelligence. During the pandemic, Lubn enables contactless property management with our wireless technology.
公司網站
https://lubn.com/
Microgreens have always been a passion for me because I love eating them and I eat them all the time. What's more efficient that growing them on my own? And since I grow them, I'm going to show you how I grow them so you can grow them too. They are extremely wonderful super nutritious powerhouses.
This video will guide from from microgreen seeds, all the way to your tummy. In this example I've used Sunflower Microgreens.
Intro by Daniel Such
https://www.youtube.com/channel/UCRy-JftlpRvSP49jH81ZTBQ
(As you guys know, I've exhausted my Sub Count trying to support small YouTubers. So I'm using Intros and YouTube Community Postings to help move your channels forward. Hope you guys can appreciate that)
#microgreens #howtogrow #raymak
?SHEET MUSIC & Mp3 ▸ http://www.makhonkit.com
?LEARN MY SONGS ▸ https://tinyurl.com/RayMak-flowkey
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?Listen on Apple Music ▸ https://music.apple.com/sg/artist/ray-mak/1498802526
?Full Song List ▸ http://www.redefiningpiano.com
Talk to me :
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more efficient 在 Man vs beast: Who is more efficient? - 6 Minute English 的推薦與評價
This week's question Efficiency involves an input and an output. ... So, according to this definition, which animal is the most efficient ? ... <看更多>