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4 changes: 1 addition & 3 deletions exercises/practice/alphametics/.docs/instructions.md
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# Instructions

Write a function to solve alphametics puzzles.
Given an alphametics puzzle, find the correct solution.

[Alphametics][alphametics] is a puzzle where letters in words are replaced with numbers.

Expand All @@ -26,6 +26,4 @@ This is correct because every letter is replaced by a different number and the w

Each letter must represent a different digit, and the leading digit of a multi-digit number must not be zero.

Write a function to solve alphametics puzzles.

[alphametics]: https://en.wikipedia.org/wiki/Alphametics
2 changes: 1 addition & 1 deletion exercises/practice/alphametics/.meta/config.json
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Expand Up @@ -17,7 +17,7 @@
".meta/proof.ci.ts"
]
},
"blurb": "Write a function to solve alphametics puzzles.",
"blurb": "Given an alphametics puzzle, find the correct solution.",
"custom": {
"version.tests.compatibility": "jest-29",
"flag.tests.task-per-describe": false,
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11 changes: 5 additions & 6 deletions exercises/practice/anagram/.docs/instructions.md
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# Instructions

Your task is to, given a target word and a set of candidate words, to find the subset of the candidates that are anagrams of the target.
Given a target word and one or more candidate words, your task is to find the candidates that are anagrams of the target.

An anagram is a rearrangement of letters to form a new word: for example `"owns"` is an anagram of `"snow"`.
A word is _not_ its own anagram: for example, `"stop"` is not an anagram of `"stop"`.

The target and candidates are words of one or more ASCII alphabetic characters (`A`-`Z` and `a`-`z`).
Lowercase and uppercase characters are equivalent: for example, `"PoTS"` is an anagram of `"sTOp"`, but `StoP` is not an anagram of `sTOp`.
The anagram set is the subset of the candidate set that are anagrams of the target (in any order).
Words in the anagram set should have the same letter case as in the candidate set.
The target word and candidate words are made up of one or more ASCII alphabetic characters (`A`-`Z` and `a`-`z`).
Lowercase and uppercase characters are equivalent: for example, `"PoTS"` is an anagram of `"sTOp"`, but `"StoP"` is not an anagram of `"sTOp"`.
The words you need to find should be taken from the candidate words, using the same letter case.

Given the target `"stone"` and candidates `"stone"`, `"tones"`, `"banana"`, `"tons"`, `"notes"`, `"Seton"`, the anagram set is `"tones"`, `"notes"`, `"Seton"`.
Given the target `"stone"` and the candidate words `"stone"`, `"tones"`, `"banana"`, `"tons"`, `"notes"`, and `"Seton"`, the anagram words you need to find are `"tones"`, `"notes"`, and `"Seton"`.
2 changes: 1 addition & 1 deletion exercises/practice/atbash-cipher/.docs/instructions.md
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# Instructions

Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.
Create an implementation of the Atbash cipher, an ancient encryption system created in the Middle East.

The Atbash cipher is a simple substitution cipher that relies on transposing all the letters in the alphabet such that the resulting alphabet is backwards.
The first letter is replaced with the last letter, the second with the second-last, and so on.
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2 changes: 1 addition & 1 deletion exercises/practice/atbash-cipher/.meta/config.json
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Expand Up @@ -18,7 +18,7 @@
".meta/proof.ci.ts"
]
},
"blurb": "Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.",
"blurb": "Create an implementation of the Atbash cipher, an ancient encryption system created in the Middle East.",
"custom": {
"version.tests.compatibility": "jest-29",
"flag.tests.task-per-describe": false,
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2 changes: 1 addition & 1 deletion exercises/practice/bank-account/.docs/instructions.md
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Your task is to implement bank accounts supporting opening/closing, withdrawals, and deposits of money.

As bank accounts can be accessed in many different ways (internet, mobile phones, automatic charges), your bank software must allow accounts to be safely accessed from multiple threads/processes (terminology depends on your programming language) in parallel.
For example, there may be many deposits and withdrawals occurring in parallel; you need to ensure there is no [race conditions][wikipedia] between when you read the account balance and set the new balance.
For example, there may be many deposits and withdrawals occurring in parallel; you need to ensure there are no [race conditions][wikipedia] between when you read the account balance and set the new balance.

It should be possible to close an account; operations against a closed account must fail.

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3 changes: 1 addition & 2 deletions exercises/practice/binary-search-tree/.meta/config.json
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Expand Up @@ -27,6 +27,5 @@
"flag.tests.jest": true,
"flag.tests.tstyche": false
},
"source": "Josh Cheek",
"source_url": "https://twitter.com/josh_cheek"
"source": "Josh Cheek"
}
4 changes: 2 additions & 2 deletions exercises/practice/binary-search/.docs/instructions.md
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Expand Up @@ -5,9 +5,9 @@ Your task is to implement a binary search algorithm.
A binary search algorithm finds an item in a list by repeatedly splitting it in half, only keeping the half which contains the item we're looking for.
It allows us to quickly narrow down the possible locations of our item until we find it, or until we've eliminated all possible locations.

```exercism/caution
~~~~exercism/caution
Binary search only works when a list has been sorted.
```
~~~~

The algorithm looks like this:

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3 changes: 1 addition & 2 deletions exercises/practice/clock/.meta/config.json
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Expand Up @@ -26,6 +26,5 @@
"flag.tests.jest": true,
"flag.tests.tstyche": false
},
"source": "Pairing session with Erin Drummond",
"source_url": "https://twitter.com/ebdrummond"
"source": "Pairing session with Erin Drummond"
}
28 changes: 1 addition & 27 deletions exercises/practice/collatz-conjecture/.docs/instructions.md
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# Instructions

The Collatz Conjecture or 3x+1 problem can be summarized as follows:

Take any positive integer n.
If n is even, divide n by 2 to get n / 2.
If n is odd, multiply n by 3 and add 1 to get 3n + 1.
Repeat the process indefinitely.
The conjecture states that no matter which number you start with, you will always reach 1 eventually.

Given a number n, return the number of steps required to reach 1.

## Examples

Starting with n = 12, the steps would be as follows:

0. 12
1. 6
2. 3
3. 10
4. 5
5. 16
6. 8
7. 4
8. 2
9. 1

Resulting in 9 steps.
So for input n = 12, the return value would be 9.
Given a positive integer, return the number of steps it takes to reach 1 according to the rules of the Collatz Conjecture.
28 changes: 28 additions & 0 deletions exercises/practice/collatz-conjecture/.docs/introduction.md
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# Introduction

One evening, you stumbled upon an old notebook filled with cryptic scribbles, as though someone had been obsessively chasing an idea.
On one page, a single question stood out: **Can every number find its way to 1?**
It was tied to something called the **Collatz Conjecture**, a puzzle that has baffled thinkers for decades.

The rules were deceptively simple.
Pick any positive integer.

- If it's even, divide it by 2.
- If it's odd, multiply it by 3 and add 1.

Then, repeat these steps with the result, continuing indefinitely.

Curious, you picked number 12 to test and began the journey:

12 ➜ 6 ➜ 3 ➜ 10 ➜ 5 ➜ 16 ➜ 8 ➜ 4 ➜ 2 ➜ 1

Counting from the second number (6), it took 9 steps to reach 1, and each time the rules repeated, the number kept changing.
At first, the sequence seemed unpredictable — jumping up, down, and all over.
Yet, the conjecture claims that no matter the starting number, we'll always end at 1.

It was fascinating, but also puzzling.
Why does this always seem to work?
Could there be a number where the process breaks down, looping forever or escaping into infinity?
The notebook suggested solving this could reveal something profound — and with it, fame, [fortune][collatz-prize], and a place in history awaits whoever could unlock its secrets.

[collatz-prize]: https://mathprize.net/posts/collatz-conjecture/
6 changes: 3 additions & 3 deletions exercises/practice/collatz-conjecture/.meta/config.json
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Expand Up @@ -17,7 +17,7 @@
".meta/proof.ci.ts"
]
},
"blurb": "Calculate the number of steps to reach 1 using the Collatz conjecture",
"blurb": "Calculate the number of steps to reach 1 using the Collatz conjecture.",
"custom": {
"version.tests.compatibility": "jest-29",
"flag.tests.task-per-describe": false,
Expand All @@ -26,6 +26,6 @@
"flag.tests.jest": true,
"flag.tests.tstyche": false
},
"source": "An unsolved problem in mathematics named after mathematician Lothar Collatz",
"source_url": "https://en.wikipedia.org/wiki/3x_%2B_1_problem"
"source": "Wikipedia",
"source_url": "https://en.wikipedia.org/wiki/Collatz_conjecture"
}
107 changes: 89 additions & 18 deletions exercises/practice/complex-numbers/.docs/instructions.md
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# Instructions

A complex number is a number in the form `a + b * i` where `a` and `b` are real and `i` satisfies `i^2 = -1`.
A **complex number** is expressed in the form `z = a + b * i`, where:

`a` is called the real part and `b` is called the imaginary part of `z`.
The conjugate of the number `a + b * i` is the number `a - b * i`.
The absolute value of a complex number `z = a + b * i` is a real number `|z| = sqrt(a^2 + b^2)`. The square of the absolute value `|z|^2` is the result of multiplication of `z` by its complex conjugate.
- `a` is the **real part** (a real number),

The sum/difference of two complex numbers involves adding/subtracting their real and imaginary parts separately:
`(a + i * b) + (c + i * d) = (a + c) + (b + d) * i`,
`(a + i * b) - (c + i * d) = (a - c) + (b - d) * i`.
- `b` is the **imaginary part** (also a real number), and

Multiplication result is by definition
`(a + i * b) * (c + i * d) = (a * c - b * d) + (b * c + a * d) * i`.
- `i` is the **imaginary unit** satisfying `i^2 = -1`.

The reciprocal of a non-zero complex number is
`1 / (a + i * b) = a/(a^2 + b^2) - b/(a^2 + b^2) * i`.
## Operations on Complex Numbers

Dividing a complex number `a + i * b` by another `c + i * d` gives:
`(a + i * b) / (c + i * d) = (a * c + b * d)/(c^2 + d^2) + (b * c - a * d)/(c^2 + d^2) * i`.
### Conjugate

Raising e to a complex exponent can be expressed as `e^(a + i * b) = e^a * e^(i * b)`, the last term of which is given by Euler's formula `e^(i * b) = cos(b) + i * sin(b)`.
The conjugate of the complex number `z = a + b * i` is given by:

Implement the following operations:
```text
zc = a - b * i
```

- addition, subtraction, multiplication and division of two complex numbers,
- conjugate, absolute value, exponent of a given complex number.
### Absolute Value

Assume the programming language you are using does not have an implementation of complex numbers.
The absolute value (or modulus) of `z` is defined as:

```text
|z| = sqrt(a^2 + b^2)
```

The square of the absolute value is computed as the product of `z` and its conjugate `zc`:

```text
|z|^2 = z * zc = a^2 + b^2
```

### Addition

The sum of two complex numbers `z1 = a + b * i` and `z2 = c + d * i` is computed by adding their real and imaginary parts separately:

```text
z1 + z2 = (a + b * i) + (c + d * i)
= (a + c) + (b + d) * i
```

### Subtraction

The difference of two complex numbers is obtained by subtracting their respective parts:

```text
z1 - z2 = (a + b * i) - (c + d * i)
= (a - c) + (b - d) * i
```

### Multiplication

The product of two complex numbers is defined as:

```text
z1 * z2 = (a + b * i) * (c + d * i)
= (a * c - b * d) + (b * c + a * d) * i
```

### Reciprocal

The reciprocal of a non-zero complex number is given by:

```text
1 / z = 1 / (a + b * i)
= a / (a^2 + b^2) - b / (a^2 + b^2) * i
```

### Division

The division of one complex number by another is given by:

```text
z1 / z2 = z1 * (1 / z2)
= (a + b * i) / (c + d * i)
= (a * c + b * d) / (c^2 + d^2) + (b * c - a * d) / (c^2 + d^2) * i
```

### Exponentiation

Raising _e_ (the base of the natural logarithm) to a complex exponent can be expressed using Euler's formula:

```text
e^(a + b * i) = e^a * e^(b * i)
= e^a * (cos(b) + i * sin(b))
```

## Implementation Requirements

Given that you should not use built-in support for complex numbers, implement the following operations:

- **addition** of two complex numbers
- **subtraction** of two complex numbers
- **multiplication** of two complex numbers
- **division** of two complex numbers
- **conjugate** of a complex number
- **absolute value** of a complex number
- **exponentiation** of _e_ (the base of the natural logarithm) to a complex number
4 changes: 2 additions & 2 deletions exercises/practice/darts/.docs/instructions.md
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# Instructions

Write a function that returns the earned points in a single toss of a Darts game.
Calculate the points scored in a single toss of a Darts game.

[Darts][darts] is a game where players throw darts at a [target][darts-target].

Expand All @@ -16,7 +16,7 @@ In our particular instance of the game, the target rewards 4 different amounts o
The outer circle has a radius of 10 units (this is equivalent to the total radius for the entire target), the middle circle a radius of 5 units, and the inner circle a radius of 1.
Of course, they are all centered at the same point — that is, the circles are [concentric][] defined by the coordinates (0, 0).

Write a function that given a point in the target (defined by its [Cartesian coordinates][cartesian-coordinates] `x` and `y`, where `x` and `y` are [real][real-numbers]), returns the correct amount earned by a dart landing at that point.
Given a point in the target (defined by its [Cartesian coordinates][cartesian-coordinates] `x` and `y`, where `x` and `y` are [real][real-numbers]), calculate the correct score earned by a dart landing at that point.

## Credit

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2 changes: 1 addition & 1 deletion exercises/practice/darts/.meta/config.json
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Expand Up @@ -16,7 +16,7 @@
".meta/proof.ci.ts"
]
},
"blurb": "Write a function that returns the earned points in a single toss of a Darts game.",
"blurb": "Calculate the points scored in a single toss of a Darts game.",
"custom": {
"version.tests.compatibility": "jest-29",
"flag.tests.task-per-describe": false,
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50 changes: 34 additions & 16 deletions exercises/practice/eliuds-eggs/.docs/introduction.md
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Expand Up @@ -12,36 +12,54 @@ The position information encoding is calculated as follows:
2. Convert the number from binary to decimal.
3. Show the result on the display.

Example 1:
## Example 1

![Seven individual nest boxes arranged in a row whose first, third, fourth and seventh nests each have a single egg.](https://assets.exercism.org/images/exercises/eliuds-eggs/example-1-coop.svg)

```text
Chicken Coop:
_ _ _ _ _ _ _
|E| |E|E| | |E|
```

### Resulting Binary

![1011001](https://assets.exercism.org/images/exercises/eliuds-eggs/example-1-binary.svg)

```text
_ _ _ _ _ _ _
|1|0|1|1|0|0|1|
```

Resulting Binary:
1 0 1 1 0 0 1
### Decimal number on the display

Decimal number on the display:
89

Actual eggs in the coop:
### Actual eggs in the coop

4

## Example 2

![Seven individual nest boxes arranged in a row where only the fourth nest has an egg.](https://assets.exercism.org/images/exercises/eliuds-eggs/example-2-coop.svg)

```text
_ _ _ _ _ _ _
| | | |E| | | |
```

Example 2:
### Resulting Binary

![0001000](https://assets.exercism.org/images/exercises/eliuds-eggs/example-2-binary.svg)

```text
Chicken Coop:
_ _ _ _ _ _ _ _
| | | |E| | | | |
_ _ _ _ _ _ _
|0|0|0|1|0|0|0|
```

Resulting Binary:
0 0 0 1 0 0 0 0
### Decimal number on the display

Decimal number on the display:
16
8

### Actual eggs in the coop

Actual eggs in the coop:
1
```
2 changes: 1 addition & 1 deletion exercises/practice/eliuds-eggs/.meta/config.json
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Expand Up @@ -23,5 +23,5 @@
"flag.tests.tstyche": false
},
"source": "Christian Willner, Eric Willigers",
"source_url": "https://forum.exercism.org/t/new-exercise-suggestion-eliuds-eggs/7632/5"
"source_url": "https://forum.exercism.org/t/new-exercise-suggestion-pop-count/7632/5"
}
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