风雨彩虹

    public interface IGraph<TVertex>
    {
        IEnumerable<IEdge<TVertex>> Edges { get; }
    }

    public interface IEdge<TVertex>
    {
        TVertex From { get; set; }
        TVertex To { get; set; }
    }

    public interface INode
    {
        IEnumerable<TNode> GetNextNodes<TNode>() where TNode : INode;
    }

    public class Edge<TVertex> : IEdge<TVertex>
    {
        public TVertex From { get; set; }
        public TVertex To { get; set; }
    }

    public static class NodeVisitor
    {
        public static void BreadthVisit<TNode>(TNode rootNode, Action<TNode> visitAction)
           where TNode : INode
        {
            BreadthVisit(rootNode, n => n.GetNextNodes<TNode>(), visitAction);
        }

        public static void BreadthVisit<TNode>(TNode rootNode, Func<TNode,IEnumerable<TNode>> nextNodeSelector, Action<TNode> visitAction)
        {
            var nodeQueue = new Queue<TNode>();
            nodeQueue.Enqueue(rootNode);
            while (nodeQueue.Any())
            {
                var currentNode = nodeQueue.Dequeue();
                if (visitAction != null)
                {
                    visitAction(currentNode);
                }
                foreach (var nextNode in nextNodeSelector(currentNode))
                {
                    nodeQueue.Enqueue(nextNode);
                }
            }
        }

        public static void DepthVisit<TNode>(TNode rootNode, Func<TNode, IEnumerable<TNode>> nextNodeSelector, Action<TNode> visitAction)
        {
            var nodeStack = new Stack<TNode>();
            nodeStack.Push(rootNode);
            while (nodeStack.Any())
            {
                var currentNode = nodeStack.Pop();
                if (visitAction != null)
                {
                    visitAction(currentNode);
                }
                foreach (var nextNode in nextNodeSeletor(currentNode))
                {
                    nodeStack.Push(nextNode);
                }
            }
        }

        public static void DepthVisit<TNode>(TNode rootNode, Action<TNode> visitAction)
           where TNode : INode
        {
            DepthVisit(rootNode, n => n.GetNextNodes<TNode>(), visitAction);
        }
    }

    public class GraphVisitor<TVertex> 
    {
        private IGraph<TVertex> _graph;

        public GraphVisitor(IGraph<TVertex> graph)
        {
            _graph = graph;
        }

        public TVertex GetRoot()
        {
            var vertexs = _graph.Edges.Select(t => t.From).Concat(_graph.Edges.Select(t => t.To));
            var toVertexs = _graph.Edges.Select(t => t.To);
            return vertexs.FirstOrDefault(t => toVertexs.All(v => !v.Equals(t)));
        }

        public IEnumerable<TVertex> GetNextVertexs(TVertex current)
        {
            return _graph.Edges.Where(t => t.From.Equals(current)).Select(t => t.To);
        }

        public void BreadthVisit(Action<TVertex> visitAction, TVertex startVertex)
        {
            NodeVisitor.BreadthVisit(startVertex, t => GetNextVertexs(t), visitAction);
        }

        public void BreadthVisit(Action<TVertex> visitAction)
        {
            NodeVisitor.BreadthVisit(GetRoot(), t => GetNextVertexs(t), visitAction);
        }

        public void DepthVisit(Action<TVertex> visitAction, TVertex startVertex)
        {
            NodeVisitor.DepthVisit(startVertex, t => GetNextVertexs(t), visitAction);
        }

        public void DepthVisit(Action<TVertex> visitAction)
        {
            NodeVisitor.DepthVisit(GetRoot(), t => GetNextVertexs(t), visitAction);
        }

        private class GraphNode : INode
        {
            private IList<INode> nodes = new List<INode>();

            public string Id { get; set; }

            public void AddNext(INode node)
            {
                nodes.Add(node);
            }

            public IEnumerable<TNode> GetNextNodes<TNode>() where TNode : INode
            {
                return nodes.Cast<TNode>();
            }
        }
    }