static void Main(string[] args)
{
var result = Precalculations.ReadFromFile(args[0]);
try
{
var answer = KruskalAlgorithm.GetMinimumSpanningTree(result.Item1, result.Item2);
using (var writer = new StreamWriter(args[1], false))
{
answer = answer.OrderBy(x => x.Start).ToList();
int start = -1;
foreach (var current in answer)
{
if (start == current.Start)
{
writer.Write($"{current.Finish} ({-current.Weight}) ");
continue;
}
start = current.Start;
writer.Write($"\n{start}: {current.Finish} ({-current.Weight}) ");
}
}
}
catch (UnconnectedGraphException exception)
{
Console.Error.WriteLine(exception.Message);
Environment.Exit(-1);
}
}
/// <summary>
/// Makes minimum spanning tree
/// </summary>
/// <param name="edges">List of graph edges</param>
/// <param name="nodes">List of graph nodes</param>
/// <returns>Minimum spanning tree</returns>
public static List <Edge> GetMinimumSpanningTree(List <Edge> edges, HashSet <int> nodes)
{
if (!Precalculations.CheckConnectivity(nodes.Count, edges))
{
throw new UnconnectedGraphException();
}
var resultList = new List <Edge>();
var dsu = new DSU();
foreach (var node in nodes)
{
dsu.MakeSet(node);
}
edges = edges.OrderBy(x => x.Weight).ToList();
foreach (var currentEdge in edges)
{
int first = currentEdge.Start;
int second = currentEdge.Finish;
int weight = currentEdge.Weight;
if (dsu.FindSet(first) != dsu.FindSet(second))
{
resultList.Add(currentEdge);
dsu.UnionSet(first, second);
}
}
return(resultList);
}