chore(CSharp): Implemented Dijkstras Algorithm to Find the Shortest Path (#489)
Waqar Hassan Khan
GitHub
parent
adaf66ebb6
commit
06ab1015e8
|
|
@ -31,3 +31,4 @@ For running the `.cs` file please using [.Net Finddle](https://dotnetfiddle.net/
|
|||
## Graph
|
||||
- [Depth First Search](src/Graph/depth-first-search.cs)
|
||||
- [Kruskals Algorithm to Find Minimum Spanning Tree](src/Graph/kruskals-algorithm.cs)
|
||||
- [Dijkstras Algorithm to Find Shortest Path](src/Graph/dijkstra.cs)
|
||||
|
|
|
|||
|
|
@ -4,4 +4,8 @@
|
|||
<TargetFramework>netcoreapp3.1</TargetFramework>
|
||||
</PropertyGroup>
|
||||
|
||||
<ItemGroup>
|
||||
<PackageReference Include="OptimizedPriorityQueue" Version="5.1.0" />
|
||||
</ItemGroup>
|
||||
|
||||
</Project>
|
||||
|
|
|
|||
|
|
@ -0,0 +1,132 @@
|
|||
using Priority_Queue;
|
||||
using System;
|
||||
using System.Collections.Generic;
|
||||
using System.Linq;
|
||||
|
||||
namespace Algorithms.Graph
|
||||
{
|
||||
public class Dijkstra
|
||||
{
|
||||
class Graph
|
||||
{
|
||||
private int _totalNodes;
|
||||
private bool _directedGraph;
|
||||
private Dictionary<int, List<Tuple<int, int>>> _edges;
|
||||
private const int INFINITY = (int)1e9;
|
||||
|
||||
public Graph(int totalNodes, bool directedGraph)
|
||||
{
|
||||
_totalNodes = totalNodes;
|
||||
_directedGraph = directedGraph;
|
||||
_edges = new Dictionary<int, List<Tuple<int, int>>>();
|
||||
}
|
||||
|
||||
public void AddEdge(int source, int destination, int weight)
|
||||
{
|
||||
if(!_edges.ContainsKey(source))
|
||||
{
|
||||
_edges.Add(source, new List<Tuple<int, int>>());
|
||||
}
|
||||
_edges[source].Add(new Tuple<int, int>(destination, weight));
|
||||
|
||||
if(!_directedGraph)
|
||||
{
|
||||
if(!_edges.ContainsKey(destination))
|
||||
{
|
||||
_edges.Add(destination, new List<Tuple<int, int>>());
|
||||
}
|
||||
_edges[destination].Add(new Tuple<int, int>(source, weight));
|
||||
}
|
||||
}
|
||||
|
||||
public Object ShortestPath(int source, int destination)
|
||||
{
|
||||
List<int> parent = Enumerable.Repeat(-1, _totalNodes + 1).ToList();
|
||||
List<int> distance = Enumerable.Repeat(INFINITY, _totalNodes + 1).ToList();
|
||||
List<bool> visited = Enumerable.Repeat(false, _totalNodes + 1).ToList();
|
||||
|
||||
SimplePriorityQueue<int> pq = new SimplePriorityQueue<int>();
|
||||
pq.Enqueue(source, 0);
|
||||
distance[source] = 0;
|
||||
|
||||
while(pq.Count > 0)
|
||||
{
|
||||
int u = pq.Dequeue();
|
||||
|
||||
if(visited[u] == true || !_edges.ContainsKey(u))
|
||||
{
|
||||
continue;
|
||||
}
|
||||
|
||||
foreach(var edge in _edges[u])
|
||||
{
|
||||
if(!visited[edge.Item1] && distance[edge.Item1] > distance[u] + edge.Item2)
|
||||
{
|
||||
distance[edge.Item1] = distance[u] + edge.Item2;
|
||||
pq.Enqueue(edge.Item1, distance[edge.Item1]);
|
||||
parent[edge.Item1] = u;
|
||||
}
|
||||
}
|
||||
|
||||
visited[u] = true;
|
||||
}
|
||||
|
||||
List<int> shortestPath = new List<int>();
|
||||
int finalDestination = destination;
|
||||
|
||||
if(distance[destination] != INFINITY)
|
||||
{
|
||||
while (true)
|
||||
{
|
||||
shortestPath.Add(finalDestination);
|
||||
finalDestination = parent[finalDestination];
|
||||
|
||||
if (finalDestination == -1)
|
||||
{
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
shortestPath.Reverse();
|
||||
}
|
||||
|
||||
Object result = new
|
||||
{
|
||||
distance = distance[destination] == INFINITY ? -1 : distance[destination],
|
||||
path = shortestPath
|
||||
};
|
||||
|
||||
return result;
|
||||
}
|
||||
}
|
||||
|
||||
public static Object RunDijkstra(int totalNodes, bool isDirected, int source, int destination, List<Tuple<int, int, int>> edges)
|
||||
{
|
||||
Graph graph = new Graph(totalNodes, isDirected);
|
||||
foreach(var edge in edges)
|
||||
{
|
||||
graph.AddEdge(edge.Item1, edge.Item2, edge.Item3);
|
||||
}
|
||||
|
||||
return graph.ShortestPath(source, destination);
|
||||
}
|
||||
|
||||
public static void Main()
|
||||
{
|
||||
var result = RunDijkstra(5, true, 1, 5, new List<Tuple<int, int, int>> {
|
||||
new Tuple<int, int, int>(1, 2, 2),
|
||||
new Tuple<int, int, int>(2, 5, 8),
|
||||
new Tuple<int, int, int>(2, 3, 4),
|
||||
new Tuple<int, int, int>(4, 1, 1),
|
||||
new Tuple<int, int, int>(3, 4, 3),
|
||||
new Tuple<int, int, int>(3, 5, 1)
|
||||
});
|
||||
|
||||
int distance = (int)result.GetType().GetProperty("distance").GetValue(result, null);
|
||||
List<int> path = (List<int>)result.GetType().GetProperty("path").GetValue(result, null);
|
||||
|
||||
Console.WriteLine($"Distance: {distance}");
|
||||
Console.WriteLine($"Path: {string.Join("->", path)}");
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -0,0 +1,54 @@
|
|||
using System;
|
||||
using NUnit.Framework;
|
||||
using System.Collections.Generic;
|
||||
|
||||
namespace Algorithms.Tests.Graph
|
||||
{
|
||||
[TestFixture]
|
||||
public class Dijkstra
|
||||
{
|
||||
static object[] TestCasesForDijkstra =
|
||||
{
|
||||
new object[]
|
||||
{
|
||||
5, false, 1, 5, new List<Tuple<int, int, int>> {
|
||||
new Tuple<int, int, int>(1, 2, 2),
|
||||
new Tuple<int, int, int>(2, 5, 5),
|
||||
new Tuple<int, int, int>(2, 3, 4),
|
||||
new Tuple<int, int, int>(1, 4, 1),
|
||||
new Tuple<int, int, int>(4, 3, 3),
|
||||
new Tuple<int, int, int>(3, 5, 1)
|
||||
},
|
||||
5
|
||||
},
|
||||
new object[]
|
||||
{
|
||||
5, true, 1, 5, new List<Tuple<int, int, int>> {
|
||||
new Tuple<int, int, int>(1, 2, 2),
|
||||
new Tuple<int, int, int>(2, 5, 8),
|
||||
new Tuple<int, int, int>(2, 3, 4),
|
||||
new Tuple<int, int, int>(4, 1, 1),
|
||||
new Tuple<int, int, int>(3, 4, 3),
|
||||
new Tuple<int, int, int>(3, 5, 1)
|
||||
},
|
||||
7
|
||||
},
|
||||
new object[]
|
||||
{
|
||||
3, false, 1, 3, new List<Tuple<int, int, int>> {
|
||||
new Tuple<int, int, int>(1, 2, 1)
|
||||
},
|
||||
-1
|
||||
},
|
||||
};
|
||||
|
||||
[TestCaseSource(nameof(TestCasesForDijkstra))]
|
||||
public void TestDijkstra_ShouldGetExpectedResult(int totalNodes, bool isDirected, int source, int destination, List<Tuple<int, int, int>> edges, int expected)
|
||||
{
|
||||
var result = Algorithms.Graph.Dijkstra.RunDijkstra(totalNodes, isDirected, source, destination, edges);
|
||||
int distance = (int)result.GetType().GetProperty("distance").GetValue(result, null);
|
||||
|
||||
Assert.AreEqual(expected, distance);
|
||||
}
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue