algorithms-and-data-structures/AlgorithmsAndDataStructures.Tests/Algorithm/Graph/FloydWarshallTests.cs at master · arst/algorithms-and-data-structures · GitHub

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using System.Collections.Generic;
using AlgorithmsAndDataStructures.Algorithms.Graph.Common;
using AlgorithmsAndDataStructures.Algorithms.Graph.ShortestPath;
using Xunit;

namespace AlgorithmsAndDataStructures.Tests.Algorithm.Graph;

public class FloydWarshallTests
{
    [Fact]
    public void CanCalculateMinDistancesForGraphWithCycles()
    {
        var sut = new FloydWarshall();

        var graph = new WeightedGraphVertex[4];

        var node1 = new WeightedGraphVertex
        {
            Edges = new List<WeightedGraphNodeEdge>
            {
                new() { To = 2, Weight = 3 },
                new() { To = 3, Weight = 0 }
            }
        };
        var node2 = new WeightedGraphVertex
        {
            Edges = new List<WeightedGraphNodeEdge>
            {
                new() { To = 0, Weight = -2 },
                new() { To = 3, Weight = 1 }
            }
        };
        var node3 = new WeightedGraphVertex
        {
            Edges = new List<WeightedGraphNodeEdge>
            {
                new() { To = 3, Weight = 5 }
            }
        };
        var node4 = new WeightedGraphVertex
        {
            Edges = new List<WeightedGraphNodeEdge>
            {
                new() { To = 1, Weight = 4 }
            }
        };

        graph[0] = node1;
        graph[1] = node2;
        graph[2] = node3;
        graph[3] = node4;

        var (distances, path) = sut.MinDistances(graph);

        Assert.Collection(distances[0],
            arg => Assert.Equal(0, arg),
            arg => Assert.Equal(4, arg),
            arg => Assert.Equal(3, arg),
            arg => Assert.Equal(0, arg));
        Assert.Collection(distances[1],
            arg => Assert.Equal(-2, arg),
            arg => Assert.Equal(0, arg),
            arg => Assert.Equal(1, arg),
            arg => Assert.Equal(-2, arg));
        Assert.Collection(distances[2],
            arg => Assert.Equal(7, arg),
            arg => Assert.Equal(9, arg),
            arg => Assert.Equal(0, arg),
            arg => Assert.Equal(5, arg));
        Assert.Collection(distances[3],
            arg => Assert.Equal(2, arg),
            arg => Assert.Equal(4, arg),
            arg => Assert.Equal(5, arg),
            arg => Assert.Equal(0, arg));
    }

    [Fact]
    public void CanCalculateMinDistancesForGraphWithoutCycles()
    {
        var sut = new FloydWarshall();

        var graph = new WeightedGraphVertex[4];

        var node1 = new WeightedGraphVertex
        {
            Edges = new List<WeightedGraphNodeEdge>
            {
                new() { To = 1, Weight = 5 },
                new() { To = 3, Weight = 30 }
            }
        };
        var node2 = new WeightedGraphVertex
        {
            Edges = new List<WeightedGraphNodeEdge>
            {
                new() { To = 2, Weight = 5 },
                new() { To = 3, Weight = 20 }
            }
        };
        var node3 = new WeightedGraphVertex
        {
            Edges = new List<WeightedGraphNodeEdge>
            {
                new() { To = 3, Weight = 5 }
            }
        };
        var node4 = new WeightedGraphVertex();

        graph[0] = node1;
        graph[1] = node2;
        graph[2] = node3;
        graph[3] = node4;

        var (distances, path) = sut.MinDistances(graph);

        Assert.Collection(distances[0],
            arg => Assert.Equal(0, arg),
            arg => Assert.Equal(5, arg),
            arg => Assert.Equal(10, arg),
            arg => Assert.Equal(15, arg));
        Assert.Collection(distances[1],
            arg => Assert.Equal(int.MaxValue / 2, arg),
            arg => Assert.Equal(0, arg),
            arg => Assert.Equal(5, arg),
            arg => Assert.Equal(10, arg));
        Assert.Collection(distances[2],
            arg => Assert.Equal(int.MaxValue / 2, arg),
            arg => Assert.Equal(int.MaxValue / 2, arg),
            arg => Assert.Equal(0, arg),
            arg => Assert.Equal(5, arg));
        Assert.Collection(distances[3],
            arg => Assert.Equal(int.MaxValue / 2, arg),
            arg => Assert.Equal(int.MaxValue / 2, arg),
            arg => Assert.Equal(int.MaxValue / 2, arg),
            arg => Assert.Equal(0, arg));
    }
}