關於 interesting number ，我們在網路上蒐集到這些相關的討論、資訊與評價

Working hard to achieve the healthy and fit body goals before the year end festive season? While its important to increase physical workouts, changing the daily food routine would be a great help too. Healthy foods often give people the impression that they are bland, dry and boring but the team at Pantai Hospital Penang has put in great effort to make things interesting. "Nutra By Pantai" is a new division of service established by the hospital which aims to provide a continuity of care to patients after hospitalization and to take care the wellbeing of the community by offering them suitable healthy food options. All meal recipes are carefully screened through and prepared by a team of experts and are prepared from fresh ingredients with stringent quality control measures to ensure food safety. Amongst the 4 major services provided by "Nutra By Pantai" are Therapeutic Meals, Get Fit Meals, Healthy Snacks and Bakery.

[Post-Surgery Meal] Stuffed Cabbage with Fish and Chicken Meat Ball Soup
[Post-Surgery Meal] Portuguese Style Fish Stew and Mashed Chickpea
[Healthy-Balanced Meal] Honey Grilled Chicken with Green Apple Salad
[Healthy-Balanced Meal] Tom Yam Fish
[Diabetic-Friendly Meal] Chicken Tangine
[Diabetic-Friendly Meal] Teo Chew Style Steamed Fish
[Heart-Healthy Meal] Pan Fried Salmon Quinoa Bowl
[Heart-Healthy Meal] Thai Basil Minced Chicken

How To Order:

Register an account via Pantai Hospital Penang App and hop over to "Nutra By Pantai" and choose the meal as well as effective date. Basic information like address will be required and you will be prompted to check out for payment. The delivery fee will be automatically calculated based on the delivery address.

Additional Information:
Pork-Free
Service Charge: Included in the price
Address: 82, Jalan Tengah, Bayan Baru, 11900, Bayan Lepas, Penang.
Business Hours (for the hospital): 8:30 am to 5 pm on weekdays, 8:30 am to 1 pm on Saturdays. Closed on Sundays.
Contact Number: 604- 643 3888 (or Whatsapp 019-759 8938)

More information on the blog soon!

📜 [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

有一個comment 說：這是我在這星期看過最有趣的東西。我會強烈建議他來香港看看。The most interesting的人種，一定是 ＃香港人。

?? This is Mong Cai central market. It may look like a normal market from the outside and inside, but trust me, this market is one of a kind. According to recourses I read before visiting this market, most of the stalls used to have two workers - 1 Vietnamese and 1 Chinese, in order to communicate with the large number of both Vietnamese and Chinese tourists. Many of the workers speak Cantonese as well, due to Mong Cai being on the border with a Cantonese speaking province of China, Guangxi. However, the market is now almost deserted due to covid, since Vietnam isn't allowing any foreign tourists to enter. Still Max and I found some interesting people and had some funny conversations in English, Chinese, Vietnamese, French, and some random alien language. Come with us on this market hunt.

Check out Max's new channel here: https://www.youtube.com/channel/UCS0tiaCChXRF_XpU5TmlWSQ

Subtitles made and translated by the awesome Loan. Check out her drawings on Instagram: https://www.instagram.com/lucielittlethings/
Il------------------------------------------
Updates from the road:
► Instagram: https://www.instagram.com/chrismixlewis/
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#Vietnam

Today(18th March), USJ Super Nintendo World opened. I went to USJ, but I couldn't enter the area because of number restriction. It's pity, but I bought some interesting candies. They are suitable for Super Nintendo World souvenir, aren't they? Mario caramel popcorn and cookie is 2900yen(26.5USD), gold coin chocolate is 2900yen(26.5USD), crunchy chocolate is 1500yen(13.7USD), potato snacks is 1300yen(11.9USD). Which do you like?
#japanesestuffchannel, #usj, #supernintendoworld

Cup noodle-like Okonomiyaki Set by Nisshin Flour Milling Inc. It says you don't need many cooking utensils but actually you need a lot of ingredients to get 😅 At least it contains mayo and sauce in addition to the dry ingredients. Anyway, the direction was interesting. Using 14cm (5.5inch) frying pan, no pressing with spatula, resulted satisfying fluffy soufflé texture! I would vote for this trick 👍

Nisshin Okonomiyaki Cup Set
https://amzn.to/3sQ3TdG

---------------------------------
Okonomiyaki Cup Set (Fluffy Savory Japanese Pancake Recipe)

Difficulty: Easy
Time: 20min
Number of servings: 2 (14cm/5.5inch) pancakes

Ingredients:
1 Nisshin Okonomiyaki Cup Set https://amzn.to/3sQ3TdG
120ml water
220g finely chopped cabbage
100g (3.5oz.) thinly sliced pork rib
1 egg
cooking oil
Okonomiyaki sauce　https://amzn.to/3ohfhfa
mayonnaise　https://amzn.to/2KLG3P2

Directions:
1. Make Batter: In the cup, put Okonomiyaki flour and water. Mix with a spoon, a bit crumbled is okay, do not overmix.
2. Mix: Add chopped cabbage, Agedama (crunchy bits of deep fried flour-batter) and egg, then mix well. *Thinly sliced cabbage is not easy to mix with a spoon, so this is why chopped cabbage is recommended.
3. Cook: In a 14cm/5.5inch frying pan, heat cooking oil, put half of the batter, and place pork slices. Uncover and cook on medium for 4 minutes. Flip it over, COVER, and cook on medium for 5 minutes. Again, flip it over, uncover, and cook on low for 5 minutes.
4. Finish: Put Okonomiyaki sauce, mayonnaise (if you like), Katsuobushi (bonito flakes) and Aonori (green laver) to finish.

レシピ（日本語）
https://cooklabo.blogspot.com/2021/01/Okonomiyaki-Cup.html
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YouTube Audio Library
Lonesome Avenue

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