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[v3] Create instruction from prob-specs descriptions
Practice Exercises in Exercism v3 will be structured differently. One such change is that there won't be a (generated) README.md file anymore. This file will be replaced by `.docs/instructions.md` and optionally a `.docs/introduction.md` files. These files are copies of the information defined for their corresponding problem-specifications exercise (if any). The `.docs/instructions.md` file is a copy of the `instructions.md` file of the problem-specifications exercise, or if that does not exists, its `description.md` file. The new [configlet](https://github.com/exercism/configlet) version will add support for doing this syncing automatically. See [the spec](https://github.com/exercism/docs/blob/main/anatomy/tracks/practice-exercises.md) for more information.
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‎exercises/practice/accumulate/.docs/instructions.md‎

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# Instructions
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Implement the `accumulate` operation, which, given a collection and an
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operation to perform on each element of the collection, returns a new
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collection containing the result of applying that operation to each element of
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the input collection.
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Given the collection of numbers:
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- 1, 2, 3, 4, 5
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And the operation:
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- square a number (`x => x * x`)
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Your code should be able to produce the collection of squares:
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- 1, 4, 9, 16, 25
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Check out the test suite to see the expected function signature.
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## Restrictions
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Keep your hands off that collect/map/fmap/whatchamacallit functionality
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provided by your standard library!
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Solve this one yourself using other basic tools instead.

‎exercises/practice/acronym/.docs/instructions.md‎

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# Instructions
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Convert a phrase to its acronym.
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Techies love their TLA (Three Letter Acronyms)!
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Help generate some jargon by writing a program that converts a long name
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like Portable Network Graphics to its acronym (PNG).

‎exercises/practice/affine-cipher/.docs/instructions.md‎

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# Instructions
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Create an implementation of the affine cipher,
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an ancient encryption system created in the Middle East.
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The affine cipher is a type of monoalphabetic substitution cipher.
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Each character is mapped to its numeric equivalent, encrypted with
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a mathematical function and then converted to the letter relating to
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its new numeric value. Although all monoalphabetic ciphers are weak,
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the affine cypher is much stronger than the atbash cipher,
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because it has many more keys.
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The encryption function is:
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`E(x) = (ax + b) mod m`
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- where `x` is the letter's index from 0 - length of alphabet - 1
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- `m` is the length of the alphabet. For the roman alphabet `m == 26`.
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- and `a` and `b` make the key
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The decryption function is:
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`D(y) = a^-1(y - b) mod m`
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- where `y` is the numeric value of an encrypted letter, ie. `y = E(x)`
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- it is important to note that `a^-1` is the modular multiplicative inverse
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of `a mod m`
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- the modular multiplicative inverse of `a` only exists if `a` and `m` are
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coprime.
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To find the MMI of `a`:
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`an mod m = 1`
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- where `n` is the modular multiplicative inverse of `a mod m`
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More information regarding how to find a Modular Multiplicative Inverse
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and what it means can be found [here.](https://en.wikipedia.org/wiki/Modular_multiplicative_inverse)
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Because automatic decryption fails if `a` is not coprime to `m` your
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program should return status 1 and `"Error: a and m must be coprime."`
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if they are not. Otherwise it should encode or decode with the
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provided key.
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The Caesar (shift) cipher is a simple affine cipher where `a` is 1 and
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`b` as the magnitude results in a static displacement of the letters.
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This is much less secure than a full implementation of the affine cipher.
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Ciphertext is written out in groups of fixed length, the traditional group
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size being 5 letters, and punctuation is excluded. This is to make it
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harder to guess things based on word boundaries.
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## General Examples
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- Encoding `test` gives `ybty` with the key a=5 b=7
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- Decoding `ybty` gives `test` with the key a=5 b=7
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- Decoding `ybty` gives `lqul` with the wrong key a=11 b=7
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- Decoding `kqlfd jzvgy tpaet icdhm rtwly kqlon ubstx`
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- gives `thequickbrownfoxjumpsoverthelazydog` with the key a=19 b=13
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- Encoding `test` with the key a=18 b=13
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- gives `Error: a and m must be coprime.`
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- because a and m are not relatively prime
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## Examples of finding a Modular Multiplicative Inverse (MMI)
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- simple example:
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- `9 mod 26 = 9`
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- `9 * 3 mod 26 = 27 mod 26 = 1`
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- `3` is the MMI of `9 mod 26`
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- a more complicated example:
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- `15 mod 26 = 15`
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- `15 * 7 mod 26 = 105 mod 26 = 1`
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- `7` is the MMI of `15 mod 26`

‎exercises/practice/all-your-base/.docs/instructions.md‎

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# Instructions
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Convert a number, represented as a sequence of digits in one base, to any other base.
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Implement general base conversion. Given a number in base **a**,
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represented as a sequence of digits, convert it to base **b**.
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## Note
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- Try to implement the conversion yourself.
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Do not use something else to perform the conversion for you.
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## About [Positional Notation](https://en.wikipedia.org/wiki/Positional_notation)
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In positional notation, a number in base **b** can be understood as a linear
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combination of powers of **b**.
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The number 42, *in base 10*, means:
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(4 * 10^1) + (2 * 10^0)
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The number 101010, *in base 2*, means:
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(1 * 2^5) + (0 * 2^4) + (1 * 2^3) + (0 * 2^2) + (1 * 2^1) + (0 * 2^0)
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The number 1120, *in base 3*, means:
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(1 * 3^3) + (1 * 3^2) + (2 * 3^1) + (0 * 3^0)
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I think you got the idea!
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*Yes. Those three numbers above are exactly the same. Congratulations!*

‎exercises/practice/allergies/.docs/instructions.md‎

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# Instructions
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Given a person's allergy score, determine whether or not they're allergic to a given item, and their full list of allergies.
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An allergy test produces a single numeric score which contains the
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information about all the allergies the person has (that they were
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tested for).
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The list of items (and their value) that were tested are:
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* eggs (1)
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* peanuts (2)
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* shellfish (4)
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* strawberries (8)
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* tomatoes (16)
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* chocolate (32)
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* pollen (64)
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* cats (128)
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So if Tom is allergic to peanuts and chocolate, he gets a score of 34.
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Now, given just that score of 34, your program should be able to say:
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- Whether Tom is allergic to any one of those allergens listed above.
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- All the allergens Tom is allergic to.
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Note: a given score may include allergens **not** listed above (i.e.
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allergens that score 256, 512, 1024, etc.). Your program should
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ignore those components of the score. For example, if the allergy
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score is 257, your program should only report the eggs (1) allergy.

‎exercises/practice/alphametics/.docs/instructions.md‎

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# Instructions
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Write a function to solve alphametics puzzles.
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[Alphametics](https://en.wikipedia.org/wiki/Alphametics) is a puzzle where
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letters in words are replaced with numbers.
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For example `SEND + MORE = MONEY`:
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```text
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S E N D
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M O R E +
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-----------
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M O N E Y
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```
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Replacing these with valid numbers gives:
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```text
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9 5 6 7
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1 0 8 5 +
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-----------
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1 0 6 5 2
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```
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This is correct because every letter is replaced by a different number and the
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words, translated into numbers, then make a valid sum.
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Each letter must represent a different digit, and the leading digit of
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a multi-digit number must not be zero.
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Write a function to solve alphametics puzzles.

‎exercises/practice/anagram/.docs/instructions.md‎

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# Instructions
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An anagram is a rearrangement of letters to form a new word.
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Given a word and a list of candidates, select the sublist of anagrams of the given word.
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Given `"listen"` and a list of candidates like `"enlists" "google"
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"inlets" "banana"` the program should return a list containing
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`"inlets"`.

‎exercises/practice/armstrong-numbers/.docs/instructions.md‎

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# Instructions
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An [Armstrong number](https://en.wikipedia.org/wiki/Narcissistic_number) is a number that is the sum of its own digits each raised to the power of the number of digits.
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For example:
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- 9 is an Armstrong number, because `9 = 9^1 = 9`
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- 10 is *not* an Armstrong number, because `10 != 1^2 + 0^2 = 1`
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- 153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
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- 154 is *not* an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`
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Write some code to determine whether a number is an Armstrong number.

‎exercises/practice/atbash-cipher/.docs/instructions.md‎

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# Instructions
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Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.
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The Atbash cipher is a simple substitution cipher that relies on
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transposing all the letters in the alphabet such that the resulting
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alphabet is backwards. The first letter is replaced with the last
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letter, the second with the second-last, and so on.
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An Atbash cipher for the Latin alphabet would be as follows:
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```text
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Plain: abcdefghijklmnopqrstuvwxyz
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Cipher: zyxwvutsrqponmlkjihgfedcba
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```
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It is a very weak cipher because it only has one possible key, and it is
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a simple monoalphabetic substitution cipher. However, this may not have
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been an issue in the cipher's time.
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Ciphertext is written out in groups of fixed length, the traditional group size
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being 5 letters, and punctuation is excluded. This is to make it harder to guess
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things based on word boundaries.
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## Examples
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- Encoding `test` gives `gvhg`
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- Decoding `gvhg` gives `test`
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- Decoding `gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt` gives `thequickbrownfoxjumpsoverthelazydog`

‎exercises/practice/bank-account/.docs/instructions.md‎

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# Instructions
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Simulate a bank account supporting opening/closing, withdrawals, and deposits
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of money. Watch out for concurrent transactions!
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A bank account can be accessed in multiple ways. Clients can make
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deposits and withdrawals using the internet, mobile phones, etc. Shops
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can charge against the account.
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Create an account that can be accessed from multiple threads/processes
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(terminology depends on your programming language).
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It should be possible to close an account; operations against a closed
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account must fail.
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## Instructions
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Run the test file, and fix each of the errors in turn. When you get the
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first test to pass, go to the first pending or skipped test, and make
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that pass as well. When all of the tests are passing, feel free to
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submit.
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Remember that passing code is just the first step. The goal is to work
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towards a solution that is as readable and expressive as you can make
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it.
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Have fun!

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