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https://github.com/rabestro/graph-pathfinding-algorithms
Implementation and tests for graph pathfinding algorithms.
https://github.com/rabestro/graph-pathfinding-algorithms
algorithm breadth-1st-search breadth-first-search dijkstra-algorithm dijkstras-algorithm graph graph-algorithms java spock-framework spring-shell
Last synced: 8 days ago
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Implementation and tests for graph pathfinding algorithms.
- Host: GitHub
- URL: https://github.com/rabestro/graph-pathfinding-algorithms
- Owner: rabestro
- License: mit
- Created: 2021-12-26T09:51:23.000Z (almost 3 years ago)
- Default Branch: master
- Last Pushed: 2024-07-09T14:14:34.000Z (4 months ago)
- Last Synced: 2024-07-09T18:08:23.764Z (4 months ago)
- Topics: algorithm, breadth-1st-search, breadth-first-search, dijkstra-algorithm, dijkstras-algorithm, graph, graph-algorithms, java, spock-framework, spring-shell
- Language: Java
- Homepage: https://algorithms.jc.id.lv/
- Size: 609 KB
- Stars: 5
- Watchers: 3
- Forks: 0
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Codeowners: .github/CODEOWNERS
Awesome Lists containing this project
README
[](https://sonarcloud.io/summary/new_code?id=rabestro_algorithms)
# Graph search algorithms
The project implements an interface for the weighted graph, as well as two algorithms for finding a path in the graph.
There are implementations and tests for two algorithms:
- [Breadth-first search](https://en.wikipedia.org/wiki/Breadth-first_search)
- [Dijkstra's Algorithm](https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm)
The implementation is written in Java 17. [API documentation](https://algorithms.jc.id.lv/docs/api/) is available. You
can also see the [specifications](https://algorithms.jc.id.lv/docs/spock-reports/) generated with the spock-reports.
## Demo. Graph Shell
To demonstrate the work of search algorithms, I made a small console program '[Graph Shell](graph-shell/README.md)'. The program
allows you to select [one of three build-in graph samples](#Graph-Samples) and search for a path using two algorithms. The source
code of the program is located in `graph-shell` module.
[](https://asciinema.org/a/468058)
### Usage in other projects
These algorithms used in the [Hypermetro](https://rabestro.github.io/hypermetro/) project, where they are
utilized to find the optimal route in the metro schema.
## How to use the algorithms in your program
The first step is to create a graph structure. The Graph interface is generic, so you can use any Java type for vertex
and any [Number](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Number.html) type for distance.
### Example
In the following Java code we create a graph structure with eight nodes. We
use [Character](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Character.html) class for vertex
identification and [Integer](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Integer.html) for the
distance. You can see the graphic representation of the scheme [here](docs/assets/complex.gif).
```java
var graph = Graph.of(Map.of(
'A', Map.of('B', 5, 'H', 2),
'B', Map.of('A', 5, 'C', 7),
'C', Map.of('B', 7, 'D', 3, 'G', 4),
'D', Map.of('C', 20, 'E', 4),
'E', Map.of('F', 5),
'F', Map.of('G', 6),
'G', Map.of('C', 4),
'H', Map.of('G', 3)
));
```
The second step is creating a search algorithm class. You can choose one of the two algorithms.
### Example
```java
var fastest = new DijkstrasAlgorithm();
var shortest = new BreadthFirstSearch();
```
Now we can search for the route.
### Example
```java
var source = 'D';
var target = 'C';
var routeOne = shortest.findPath(graph, source, target);
var routeTwo = fastest.findPath(graph, source, target);
```
As result, you get a list with the path.
```java
routeOne==['D','C']
routeTwo==['D','E','F','G','C']
```
## Unit Tests
Tests are written in Groove language. For unit testing, the [Spock Framework](https://spockframework.org/) was used. To test the operation of the algorithms, the following sample graphs were created.
## Graph Samples
### Small Graph Sample
```mermaid
flowchart LR
A((A))
B((B))
C((C))
A -->|7| B
A -->|2| C
B -->|3| A
B -->|5| C
C -->|1| A
C -->|3| B
```
### Medium Graph Sample
```mermaid
flowchart LR
A --> |5 | B
B --> |5 | A
B --> |10| C
C --> |5 | D
C --> |20| B
D --> |5 | E
E --> |5 | B
```
### Complex Graph Sample
```mermaid
flowchart LR
A --> |5 | B
A --> |2 | H
B --> |5 | A
B --> |7 | C
C --> |7 | B
C --> |3 | D
C --> |4 | G
D --> |20| C
D --> |4 | E
E --> |5 | F
G --> |4 | C
H --> |3 | G
```
