What is wrong with mys solution - ? public static int kruskals(int gNodes, List gFrom, List gTo, List gWeight) { var edges = new List>(); for (int i = 0; i < gFrom.Count; i++) { edges.Add(new Tuple(gFrom[i], gTo[i], gWeight[i])); }

edges = edges
    .OrderBy(e => e.Item3)
    .ThenBy(e => e.Item1)
    .ToList();

var visitedNodes = new HashSet<int>();
var mstEdges = new List<Tuple<int, int, int>>();
for (int i = 0; i < edges.Count; i++)
{
    if (!visitedNodes.Contains(edges[i].Item2))
    {
        mstEdges.Add(edges[i]);
        visitedNodes.Add(edges[i].Item2);
    }
    if (mstEdges.Count == gNodes - 1)
        break;
}

var totalWeight = mstEdges.Sum(e => e.Item3);
return totalWeight;

}