├── .github
    └── workflows
    │   ├── cd.yml
    │   └── ci.yml
├── Cargo.toml
├── .gitignore
├── src
    └── lib.rs
├── LICENSE
└── README.md


/.github/workflows/cd.yml:
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 1 | name: CD
 2 | 
 3 | on:
 4 |   push:
 5 |     branches:
 6 |       - main
 7 | 
 8 | jobs:
 9 |   build:
10 |     runs-on: ubuntu-latest
11 |     steps:
12 |       - uses: actions/checkout@v3
13 |       - name: Set up Rust
14 |         uses: actions-rs/toolchain@v1
15 |         with:
16 |           toolchain: stable
17 |           override: true
18 |       - name: Build project
19 |         run: cargo build --release
20 | 


--------------------------------------------------------------------------------
/.github/workflows/ci.yml:
--------------------------------------------------------------------------------
 1 | name: CI
 2 | 
 3 | on:
 4 |   push:
 5 |     branches:
 6 |       - main
 7 |   pull_request:
 8 |     branches:
 9 |       - main
10 | 
11 | jobs:
12 |   test:
13 |     runs-on: ubuntu-latest
14 |     steps:
15 |       - uses: actions/checkout@v3
16 |       - name: Set up Rust
17 |         uses: actions-rs/toolchain@v1
18 |         with:
19 |           toolchain: stable
20 |           override: true
21 |       - name: Run tests
22 |         run: cargo test
23 | 


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/Cargo.toml:
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 1 | [package]
 2 | name = "longest-subsequence-with-decreasing-adjacent-difference"
 3 | version = "0.1.0"
 4 | edition = "2021"
 5 | authors = ["aliezzahn <aliezzahn@gmail.com>"]
 6 | description = "A Rust library to find the length of the longest subsequence with decreasing adjacent differences."
 7 | repository = "https://github.com/aliezzahn/longest-subsequence-with-decreasing-adjacent-difference"
 8 | license = "MIT"
 9 | keywords = ["subsequence", "dynamic-programming", "algorithm"]
10 | categories = ["algorithms"]
11 | 
12 | [dependencies]
13 | 
14 | [dev-dependencies]


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/.gitignore:
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 1 | # Generated by Cargo
 2 | # will have compiled files and executables
 3 | debug/
 4 | target/
 5 | 
 6 | # Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
 7 | # More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
 8 | Cargo.lock
 9 | 
10 | # These are backup files generated by rustfmt
11 | **/*.rs.bk
12 | 
13 | # MSVC Windows builds of rustc generate these, which store debugging information
14 | *.pdb
15 | 
16 | # RustRover
17 | #  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
18 | #  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
19 | #  and can be added to the global gitignore or merged into this file.  For a more nuclear
20 | #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
21 | #.idea/
22 | 
23 | # Added by cargo
24 | 
25 | /target
26 | 


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/src/lib.rs:
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 1 | /// A library to find the length of the longest subsequence with decreasing adjacent differences.
 2 | pub struct Solution;
 3 | 
 4 | impl Solution {
 5 |     pub fn longest_subsequence(nums: Vec<i32>) -> i32 {
 6 |         let n = nums.len();
 7 |         if n == 0 {
 8 |             return 0;
 9 |         }
10 | 
11 |         let mut dp = vec![1; n]; // dp[i] stores the length of the longest subsequence ending at i
12 |         let mut max_len = 1;
13 | 
14 |         for i in 1..n {
15 |             for j in 0..i {
16 |                 let diff_i_j = (nums[i] - nums[j]).abs();
17 |                 let diff_j_prev = if j > 0 { (nums[j] - nums[j - 1]).abs() } else { i32::MAX };
18 | 
19 |                 if j == 0 || diff_i_j < diff_j_prev {
20 |                     dp[i] = dp[i].max(dp[j] + 1);
21 |                 }
22 |             }
23 |             max_len = max_len.max(dp[i]);
24 |         }
25 | 
26 |         max_len
27 |     }
28 | }


--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
 1 | MIT License
 2 | 
 3 | Copyright (c) 2025 aliezza hn
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
 1 | # Longest Subsequence with Decreasing Adjacent Difference
 2 | 
 3 | A Rust library to find the length of the longest subsequence with decreasing adjacent differences.
 4 | 
 5 | ![CI](https://github.com/aliezzahn/longest-subsequence-with-decreasing-adjacent-difference/actions/workflows/ci.yml/badge.svg)
 6 | ![CD](https://github.com/aliezzahn/longest-subsequence-with-decreasing-adjacent-difference/actions/workflows/cd.yml/badge.svg)
 7 | [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 8 | 
 9 | ## Overview
10 | 
11 | Given a sequence of integers, this library computes the length of the longest subsequence where the difference between adjacent elements is strictly decreasing.
12 | 
13 | ## Installation
14 | 
15 | Add the following to your `Cargo.toml`:
16 | 
17 | ```toml
18 | [dependencies]
19 | longest-subsequence-with-decreasing-adjacent-difference = "0.1"
20 | ```
21 | 
22 | ## Usage
23 | 
24 | ```rust
25 | use longest_subsequence_with_decreasing_adjacent_difference::Solution;
26 | 
27 | fn main() {
28 |     let nums = vec![10, 20, 10, 19, 10, 20];
29 |     let result = Solution::longest_subsequence(nums);
30 |     println!("Length of the longest subsequence: {}", result);
31 | }
32 | ```
33 | 
34 | ## Example Output
35 | 
36 | For the input `[10, 20, 10, 19, 10, 20]`, the output will be:
37 | 
38 | ```
39 | Length of the longest subsequence: 5
40 | ```
41 | 
42 | ## Running Tests
43 | 
44 | To run the tests, use the following command:
45 | 
46 | ```bash
47 | cargo test
48 | ```
49 | 
50 | ## License
51 | 
52 | This project is licensed under the MIT License. See the [LICENSE](LICENSE) file for details.
53 | 
54 | ## Contributing
55 | 
56 | Contributions are welcome! Please open an issue or submit a pull request on [GitHub](https://github.com/aliezzahn/longest-subsequence-with-decreasing-adjacent-difference).
57 | 
58 | ## Contact
59 | 
60 | For questions or feedback, feel free to reach out:
61 | 
62 | - Email: [aliezzahn@gmail.com](mailto:aliezzahn@gmail.com)
63 | - GitHub: [aliezzahn](https://github.com/aliezzahn)
64 | 


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