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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/
4 changes: 2 additions & 2 deletions exercises/practice/collatz-conjecture/.meta/config.json
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]
},
"blurb": "Calculate the number of steps to reach 1 using the Collatz conjecture.",
"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"
}
2 changes: 1 addition & 1 deletion exercises/practice/grains/.meta/config.json
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},
"blurb": "Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.",
"source": "The CodeRanch Cattle Drive, Assignment 6",
"source_url": "https://coderanch.com/wiki/718824/Grains"
"source_url": "https://web.archive.org/web/20240908084142/https://coderanch.com/wiki/718824/Grains"
}
11 changes: 0 additions & 11 deletions exercises/practice/hamming/.docs/instructions.md
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Calculate the Hamming distance between two DNA strands.

Your body is made up of cells that contain DNA.
Those cells regularly wear out and need replacing, which they achieve by dividing into daughter cells.
In fact, the average human body experiences about 10 quadrillion cell divisions in a lifetime!

When cells divide, their DNA replicates too.
Sometimes during this process mistakes happen and single pieces of DNA get encoded with the incorrect information.
If we compare two strands of DNA and count the differences between them we can see how many mistakes occurred.
This is known as the "Hamming distance".

We read DNA using the letters C, A, G and T.
Two strands might look like this:

Expand All @@ -20,8 +11,6 @@ Two strands might look like this:

They have 7 differences, and therefore the Hamming distance is 7.

The Hamming distance is useful for lots of things in science, not just biology, so it's a nice phrase to be familiar with :)

## Implementation notes

The Hamming distance is only defined for sequences of equal length, so an attempt to calculate it between sequences of different lengths should not work.
12 changes: 12 additions & 0 deletions exercises/practice/hamming/.docs/introduction.md
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# Introduction

Your body is made up of cells that contain DNA.
Those cells regularly wear out and need replacing, which they achieve by dividing into daughter cells.
In fact, the average human body experiences about 10 quadrillion cell divisions in a lifetime!

When cells divide, their DNA replicates too.
Sometimes during this process mistakes happen and single pieces of DNA get encoded with the incorrect information.
If we compare two strands of DNA and count the differences between them, we can see how many mistakes occurred.
This is known as the "Hamming distance".

The Hamming distance is useful in many areas of science, not just biology, so it's a nice phrase to be familiar with :)
2 changes: 1 addition & 1 deletion exercises/practice/leap/.meta/config.json
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},
"blurb": "Determine whether a given year is a leap year.",
"source": "CodeRanch Cattle Drive, Assignment 3",
"source_url": "https://coderanch.com/t/718816/Leap"
"source_url": "https://web.archive.org/web/20240907033714/https://coderanch.com/t/718816/Leap"
}
8 changes: 3 additions & 5 deletions exercises/practice/luhn/.docs/instructions.md
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# Instructions

Given a number determine whether or not it is valid per the Luhn formula.
Determine whether a credit card number is valid according to the [Luhn formula][luhn].

The [Luhn algorithm][luhn] is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers and Canadian Social Insurance Numbers.
The number will be provided as a string.

The task is to check if a given string is valid.

## Validating a Number
## Validating a number

Strings of length 1 or less are not valid.
Spaces are allowed in the input, but they should be stripped before checking.
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11 changes: 11 additions & 0 deletions exercises/practice/luhn/.docs/introduction.md
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# Introduction

At the Global Verification Authority, you've just been entrusted with a critical assignment.
Across the city, from online purchases to secure logins, countless operations rely on the accuracy of numerical identifiers like credit card numbers, bank account numbers, transaction codes, and tracking IDs.
The Luhn algorithm is a simple checksum formula used to ensure these numbers are valid and error-free.

A batch of identifiers has just arrived on your desk.
All of them must pass the Luhn test to ensure they're legitimate.
If any fail, they'll be flagged as invalid, preventing errors or fraud, such as incorrect transactions or unauthorized access.

Can you ensure this is done right? The integrity of many services depends on you.
8 changes: 4 additions & 4 deletions exercises/practice/protein-translation/.docs/instructions.md
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Translate RNA sequences into proteins.

RNA can be broken into three nucleotide sequences called codons, and then translated to a polypeptide like so:
RNA can be broken into three-nucleotide sequences called codons, and then translated to a protein like so:

RNA: `"AUGUUUUCU"` => translates to

Codons: `"AUG", "UUU", "UCU"`
=> which become a polypeptide with the following sequence =>
=> which become a protein with the following sequence =>

Protein: `"Methionine", "Phenylalanine", "Serine"`

Expand All @@ -27,9 +27,9 @@ Protein: `"Methionine", "Phenylalanine", "Serine"`

Note the stop codon `"UAA"` terminates the translation and the final methionine is not translated into the protein sequence.

Below are the codons and resulting Amino Acids needed for the exercise.
Below are the codons and resulting amino acids needed for the exercise.

| Codon | Protein |
| Codon | Amino Acid |
| :----------------- | :------------ |
| AUG | Methionine |
| UUU, UUC | Phenylalanine |
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2 changes: 1 addition & 1 deletion exercises/practice/rna-transcription/.meta/config.json
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".meta/example.f90"
]
},
"blurb": "Given a DNA strand, return its RNA Complement Transcription.",
"blurb": "Given a DNA strand, return its RNA complement.",
"source": "Hyperphysics",
"source_url": "https://web.archive.org/web/20220408112140/http://hyperphysics.phy-astr.gsu.edu/hbase/Organic/transcription.html"
}

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