图的邻接表存储结构

程序调用入口：

using System;

namespace Graphic_AdjacencyList
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var adjacencyList = new AdjacencyList<char>();

            Console.WriteLine("1.初始化树结构：");

            Console.WriteLine("=================================");
            //添加顶点；
            adjacencyList.AddVertex('A');
            adjacencyList.AddVertex('B');
            adjacencyList.AddVertex('C');
            adjacencyList.AddVertex('D');

            //添加边；
            adjacencyList.AddEdge('A', 'B');
            adjacencyList.AddEdge('A', 'C');
            adjacencyList.AddEdge('A', 'D');
            adjacencyList.AddEdge('B', 'D');
            adjacencyList.AddEdge('C', 'D');

            Console.WriteLine("=================================");

            Console.WriteLine("2.树的邻接表遍历：");
            Console.WriteLine(adjacencyList.ToString());
            Console.Read();
        }
    }
}

图-顶点类：

namespace Graphic_AdjacencyList
{
    /// <summary>
    ///     链表中的节点
    /// </summary>
    public class Node<T>
    {
        /// <summary>
        ///     邻接点域
        /// </summary>
        public Vertex<T> Adjvex;

        /// <summary>
        ///     下一个邻接点指针域
        /// </summary>
        public Node<T> Next;

        /// <summary>
        ///     链表中的节点
        /// </summary>
        /// <param name="value"></param>
        public Node(Vertex<T> value)
        {
            Adjvex = value;
        }
    }
}

图-链表中的表头节点类：

using System;

namespace Graphic_AdjacencyList
{
    /// <summary>
    ///     链表中的表头节点
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class Vertex<T>
    {
        /// <summary>
        ///     数据
        /// </summary>
        public T Data;

        /// <summary>
        ///     邻接表表头指针
        /// </summary>
        public Node<T> FirstEdge;

        /// <summary>
        ///     访问标志，遍历时使用
        /// </summary>
        public Boolean Visited;

        /// <summary>
        ///     表头节点
        /// </summary>
        /// <param name="value"></param>
        public Vertex(T value) //构造方法；
        {
            Data = value;
        }
    }
}

 图-图的邻接表存储类：

using System;
using System.Collections.Generic;
using System.Linq;

namespace Graphic_AdjacencyList
{
    /// <summary>
    ///     图的邻接表存储类
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class AdjacencyList<T>
    {
        /// <summary>
        ///     图的顶点集合
        /// </summary>
        private readonly List<Vertex<T>> _items;

        public AdjacencyList()
            : this(10)
        {
        }

        public AdjacencyList(int capacity)
        {
            _items = new List<Vertex<T>>(capacity);
        }

        /// <summary>
        ///     添加顶点
        /// </summary>
        /// <param name="item"></param>
        public void AddVertex(T item)
        {
            if (Contains(item))
            {
                throw new ArgumentException("插入了重复顶点！");
            }
            _items.Add(new Vertex<T>(item));
            Console.WriteLine("添加顶点：" + item);
        }

        /// <summary>
        ///     添加无向边
        /// </summary>
        /// <param name="from"></param>
        /// <param name="to"></param>
        public void AddEdge(T from, T to)
        {
            Vertex<T> fromVer = Find(from);
            if (fromVer == null)
            {
                throw new ArgumentException("头顶点不存在！");
            }
            Vertex<T> toVer = Find(to);
            if (toVer == null)
            {
                throw new ArgumentException("尾顶点不存在！");
            }
            //无向边的两个顶点都需记录边信息；
            AddDirectedEdge(fromVer, toVer);
            AddDirectedEdge(toVer, fromVer);

            Console.WriteLine(string.Format("添加无向边：{0}—{1}", from, to));
        }

        /// <summary>
        ///     添加有向边
        /// </summary>
        /// <param name="fromVer"></param>
        /// <param name="toVer"></param>
        private void AddDirectedEdge(Vertex<T> fromVer, Vertex<T> toVer)
        {
            if (fromVer.FirstEdge == null) //无临接点时；
            {
                fromVer.FirstEdge = new Node<T>(toVer);
            }
            else
            {
                Node<T> tem, node = fromVer.FirstEdge;
                do
                {
                    if (node.Adjvex.Data.Equals(toVer.Data))
                    {
                        throw new ArgumentException("添加了重复的边！");
                    }
                    tem = node;
                    node = node.Next;
                } while (node != null);
                tem.Next = new Node<T>(toVer); //添加到链表末尾；
            }
        }
        public bool Contains(T item)
        {
            //foreach (Vertex<T> v in _items)
            //{
            //    if (v.data.Equals(item))
            //    {
            //        return true;
            //    }
            //}
            return _items.Any(v => v.Data.Equals(item));
        }

        private Vertex<T> Find(T item)
        {
            //foreach (Vertex<T> v in _items)
            //{
            //    if (v.data.Equals(item))
            //    {
            //        return v;
            //    }
            //}
            return _items.FirstOrDefault(v => v.Data.Equals(item));
        }

        public override string ToString()
        {
            string result = string.Empty;
            foreach (var vertex in _items)
            {
                if (vertex != null)
                {
                    result += string.Format("顶点：{0}:", vertex.Data);
                    if (vertex.FirstEdge != null)
                    {
                        Node<T> tem = vertex.FirstEdge;
                        while (tem != null)
                        {
                            result += tem.Adjvex.Data.ToString();
                            tem = tem.Next;
                        }
                    }
                }
                result += "\r\n";
            }
            return result;
        }
    }
}

执行结果：