https://github.com/aliezzahn/check-digits
A Rust library to check if digits can be equal after operations using binomial coefficients.
https://github.com/aliezzahn/check-digits
Last synced: 3 months ago
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A Rust library to check if digits can be equal after operations using binomial coefficients.
- Host: GitHub
- URL: https://github.com/aliezzahn/check-digits
- Owner: aliezzahn
- License: mit
- Created: 2025-02-25T18:20:26.000Z (3 months ago)
- Default Branch: main
- Last Pushed: 2025-02-25T18:34:30.000Z (3 months ago)
- Last Synced: 2025-02-25T19:33:51.290Z (3 months ago)
- Language: Rust
- Size: 5.86 KB
- Stars: 3
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Check Digits
A Rust library and binary to determine if a string of digits can be considered equal after certain operations, based on binomial coefficient properties modulo 2 and 5.
[](https://opensource.org/licenses/MIT)
## Overview
This project implements a solution to the "Check if Digits are Equal in String After Operations II" problem. It computes the sum of differences between consecutive digits, weighted by binomial coefficients \(\binom{n-2}{i}\), and checks if the result is zero modulo both 2 and 5. The implementation is optimized for runtime performance with:
- No heap allocations beyond the input string.
- Precomputed modular inverses for modulo 5.
- Efficient incremental updates of binomial coefficients.
- Bitwise operations for modulo 2 where applicable.
## Installation
Clone the repository and build with Cargo:
```bash
git clone https://github.com/aliezzahn/check-digits.git
cd check-digits
cargo build --release
```
### Prerequisites
- Rust (stable, edition 2021) installed via [rustup](https://rustup.rs/).
- Git for cloning the repository.
## Usage
### As a Binary
Run the prebuilt example:
```bash
cargo run --release
```
Expected output:
```
Input: 3902, Result: true
Input: 34789, Result: false
Input: 323, Result: true
Input: 355, Result: false
Input: 242, Result: true
Input: 797, Result: true
Input: 9206, Result: false
```
### As a Library
Add to your `Cargo.toml`:
```toml
[dependencies]
check-digits = { git = "https://github.com/aliezzahn/check-digits.git" }
```
Use in your code:
```rust
use check_digits::Solution;
fn main() {
let result = Solution::has_same_digits("323".to_string());
println!("Can digits be equal? {}", result); // true
}
```
## API Documentation
The library provides a single public method:
- `Solution::has_same_digits(s: String) -> bool`: Checks if the digit sequence satisfies the binomial condition.
Full documentation is available in the source code using Rustdoc. Generate and view it locally:
```bash
cargo doc --open
```
## Test Cases
The library has been verified against the following inputs:
- `"3902"` → `true`
- `"34789"` → `false`
- `"323"` → `true`
- `"355"` → `false`
- `"242"` → `true`
- `"797"` → `true`
- `"9206"` → `false`
Run tests to verify:
```bash
cargo test
```
## Performance
- **Time Complexity**: \( O(n) \) per modulus check, where \( n \) is the string length, with optimized constant factors.
- **Space Complexity**: \( O(1) \) heap usage, leveraging stack variables and string slices.
## Contributing
Contributions are welcome! Please follow these steps:
1. Fork the repository.
2. Create a new branch (`git checkout -b feature/your-feature`).
3. Commit your changes (`git commit -am 'Add your feature'`).
4. Push to the branch (`git push origin feature/your-feature`).
5. Open a Pull Request.
### Development
- Format code: `cargo fmt`
- Check linting: `cargo clippy`
- Run tests: `cargo test`
## License
This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
## Acknowledgments
- Inspired by combinatorial problems involving binomial coefficients.
- Built with Rust for performance and safety.