C#:使用Hashtable实现输出那些用户发表主题最多的信息

构思：先计算各自的数量，那些数量最多，输出详细信息

 

具体算法如下：

    public class Count
    {
        #region 计算各实体数量
        public static Hashtable EntityCount(DataTable dt, string clmnUid)
        {
            //List<string> lst = new List<string>();
            Hashtable uidsCount = new Hashtable();

            foreach( DataRow row in dt.Rows)
            {
                string uid = row[clmnUid].ToString();
                if (uidsCount.Contains(uid))
                {
                    uidsCount[uid] = (int)uidsCount[uid] + 1;
                }
                else
                {
                    uidsCount.Add(uid,1);
                }
            }
            return uidsCount;
        }
        #endregion

        #region 获取数量最多的实体

        public static IList<string> MaxCountUid(Hashtable uidsCount,bool listResult)
        {
            int maxCount = 0;
            IList<string> uids = new List<string>();
            int value = 0;
            foreach (DictionaryEntry kv in uidsCount)
            {
                value = (int)kv.Value;
                if (value > maxCount)
                {
                    maxCount = value;
                    uids.Clear();
                    uids.Add(kv.Key.ToString());
                }
                else if(value == maxCount)
                {
                    uids.Add(kv.Key.ToString());
                }
            }
            return uids;
        }

        public static Hashtable MaxCountUid(Hashtable uidsCount)
        {
            int maxCount = 0;
            Hashtable uids = new Hashtable();
            int value = 0;
            foreach (DictionaryEntry kv in uidsCount)
            {
                value = (int)kv.Value;
                if (value > maxCount)
                {
                    maxCount = value;
                    uids.Clear();
                    uids.Add(kv.Key,kv.Value);
                }
                else if (value == maxCount)
                {
                    uids.Add(kv.Key, kv.Value);
                }
            }
            return uids;
        }

        #endregion

        #region 输出用户的ID、姓名、数量

        public static void PrintMaxCountName(IList<string> uids,DataTable users, string clmnUid, string clmnName)
        { 
            foreach(DataRow dr in users.Rows)
            {
                string strUid = dr[clmnUid].ToString();
                foreach(string uid in uids)
                {
                    if (uid == strUid)
                    {
                        string strName = dr[clmnName].ToString();
                        Console.WriteLine(strUid + ":" + strName);
                    }
                }
            }
        }

        public static void PrintMaxCountName(Hashtable uids, DataTable users, string clmnUid, string clmnName)
        {
            foreach (DataRow dr in users.Rows)
            {
                string strUid = dr[clmnUid].ToString();
                foreach (DictionaryEntry kv in uids)
                {
                    if (kv.Key.ToString() == strUid)
                    {
                        string strName = dr[clmnName].ToString();
                        Console.WriteLine(strUid + ":" + strName +"(" + kv.Value.ToString() + ")");
                    }
                }
            }
        }

        #endregion
    }

构造测试数据：

    public class Data
    {
        private string[] usersColumns = { "uid", "name" };
        private string[] subjectsColumns = { "title", "uid", "time" };

        public DataTable initUsers()
        {
            DataTable users = new DataTable();
            foreach (string columnName in usersColumns)
            {
                users.Columns.Add(columnName);
            }

            for (int i = 0; i < 10;i++ )
            {
                users.Rows.Add("uid"+i,"name"+i);
            }

            return users;
        }

        public DataTable initSujects()
        {
            DataTable subjects = new DataTable();
            foreach (string columnName in subjectsColumns)
            {
                subjects.Columns.Add(columnName);
            }

            for (int i = 0; i < 123; i++)
            {
                subjects.Rows.Add("title" + i, "uid" + i % 10,"time" + 1);
            }

            return subjects;
        }
    }

测试代码：

    class Program
    {
        
        static void Main(string[] args)
        {
            const string clmnUid = "uid";
            const string clmnName = "name";
            Data data = new Data();
            DataTable users = data.initUsers();
            DataTable subjects = data.initSujects();

            Hashtable uidsCount = Count.EntityCount(subjects, clmnUid);
            Hashtable maxCountUids = Count.MaxCountUid(uidsCount);
            Count.PrintMaxCountName(maxCountUids,users,clmnUid,clmnName);

            Console.Read();
        }
    }

输出结果：
uid0:name0(13)

uid1:name1(13)

uid2:name2(13)