C#有向图拓扑排序

    /// <summary>
    /// 图的节点类
    /// </summary>
    public class GraphNode
    {
        private int inDegree;
        private int outDegree;
        private string nodeName;

        /// <summary>
        /// 节点入度
        /// </summary>
        public int InDegree
        {
            set { inDegree = value; }
            get { return inDegree; }
        }

        /// <summary>
        /// 节点出度
        /// </summary>
        public int OutDegree
        {
            set { outDegree = value; }
            get { return outDegree; }
        }

        /// <summary>
        /// 节点名称
        /// </summary>
        public string NodeName
        {
            get { return nodeName; }
        }

        /// <summary>
        /// 构造函数
        /// </summary>
        public GraphNode()
        {
        }

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name='nodeName'>节点名称</param>
        public GraphNode(string nodeName)
        {
            this.nodeName = nodeName;
        }
    }

 

    /// <summary>
    /// 有向图的排序算法类
    /// </summary>
    public class GraphDirecTopoSorted
    {
        private List<GraphNode> nodeList;   //节点链表
        private List<KeyValuePair<GraphNode, GraphNode>> edgeList;  //边链表

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name='node'>节点链表</param>
        /// <param name='edge'>边链表</param>
        public GraphDirecTopoSorted(List<GraphNode> node, List<KeyValuePair<GraphNode, GraphNode>> edge)
        {
            this.nodeList = node;
            this.edgeList = edge;
        }

        /// <summary>
        /// 计算节点的入度出度
        /// </summary>
        private void NodeInOutDegree()
        {
            foreach (GraphNode node in nodeList)
            {
                int inDegree = 0;
                int outDegree = 0;
                foreach (KeyValuePair<GraphNode, GraphNode> edge in edgeList)
                {
                    if (edge.Value.NodeName == node.NodeName)
                    {
                        inDegree++;
                    }
                    if (edge.Key.NodeName == node.NodeName)
                    {
                        outDegree++;
                    }
                }
                node.InDegree = inDegree;
                node.OutDegree = outDegree;
            }
        }

        /// <summary>
        /// 是否有环路，有则返回NULL，否则返回入度为零的节点
        /// </summary>
        /// <returns>入度为零的节点</returns>
        private GraphNode HaveCycle()
        {
            GraphNode tempNode = new GraphNode();
            NodeInOutDegree();
            foreach (GraphNode node in nodeList)
            {
                if (node.InDegree == 0)
                {
                    tempNode = node;
                }
            }
            return tempNode;
        }

        /// <summary>
        /// 删除节点对应的边
        /// </summary>
        /// <param name='node'>节点</param>
        private void RemoveGraphEdge(GraphNode node)
        {
            for (int i = 0; i < edgeList.Count; )
            {
                if (edgeList[i].Key == node)
                {
                    edgeList.RemoveAt(i);
                }
                else
                {
                    i++;
                }
            }
        }

        /// <summary>
        /// 有向图的排序
        /// </summary>
        /// <returns>排序后的节点链表</returns>
        public List<GraphNode> TopoSorted()
        {
            List<GraphNode> sortResult = new List<GraphNode>();
            while (nodeList.Count > 0)
            {
                GraphNode tempNode = HaveCycle();
                if (tempNode != null)
                {
                    sortResult.Add(tempNode);
                    nodeList.Remove(tempNode);
                    RemoveGraphEdge(tempNode);
                }
            }
            return sortResult;
        }
    }