Turnip Price

中文版

A Rust (and WebAssembly) implementation of the calculator turnip price of Animal Crossing: New Horizon. This project can't be done without @_Ninji's C++ code and his disassembly work. You can try the demo online.

🚀 Getting Started

You can install this package via npm or Yarn.

npm i turnip-price
# or
yarn add turnip-price

Also, make sure that the target environment has access to WebAssembly. Then you can write a calculation function like this.

import * as wasm from "turnip-price";
import { memory } from 'turnip-price/turnip_price_bg';

function calculate(whatPattern, seed) {
  const turnip = wasm.calculate(whatPattern, seed);
  return {
    buyingPrice: trunip.buying_price,
    sellingPrices: new Int32Array(memory.buffer, turnip.selling_prices(), 12),
  };
}

Explanation of the sellingPrices array:

• The 0th, 2nd, 4th, 6th, 8th, 10th elements indicate the morning price from Tuesday to Saturday respectively;
• The 1st, 3rd, 5th, 7th, 9th, 11th elements indicate the afternoon price from Tuesday to Saturday respectively.

🤔 FAQ

📈 Can I Predict the Price on My Island by This?

No, yet. Because you don't have the random seed, which is not exposed to regular players. By the way, if you have the seed, the calculator won't work the first time you buy the turnips, according to @_Ninji's reply.

🕸️🦀️ Why do you use WebAssembly?

Because the code involves the practice of reinterpreting unsigned 32-bit integer as 32-bit IEEE 754 floating number. Though I can do that in JavaScript, using WebAssembly maybe more stable.

🔍 Discovery

📚 Can I Enumerate All Combinations?

There are total 4 × 2 ^ 32 = 17,179,869,184 combinations. On my machine, it tooks 4 minutes to enumerate all combinations (in 4 threads).

However, it's cost to save all combinations to your disk. For each combination, the algorithm will product 13 prices. Each price is a positive integer from 0 to around 660, which can be represented by an unsigned 10-bit integer. Therefore, the uncompressed data size is 2,233,382,993,920 bits, i.e. 260 GBs.

💰 How Much Is The Highest Price?

I tried all combinations of patterns (0, 1, 2, 3) and seeds (from 0 to UINT32_MAX). Here is the results.

• In pattern 0 (i.e. what_pattern is set to 0), the highest price is 660 when seed = 326.
• In pattern 1 (i.e. what_pattern is set to 1), the highest price is 660 when seed = 326.
• In pattern 2 (i.e. what_pattern is set to 2), the highest price is 660 when seed = 326.
• In pattern 3 (i.e. what_pattern is set to 3), the highest price is 660 when seed = 9772.

In conclusion, the highest price of turnips is 660.

📈 Weekly Highest Price Distribution

You may want to acknowledge the distribtion. I also did this.