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] + ;
}
else
{
uidsCount.Add(uid,);
}
}
return uidsCount;
}
#endregion #region 获取数量最多的实体 public static IList<string> MaxCountUid(Hashtable uidsCount,bool listResult)
{
int maxCount = ;
IList<string> uids = new List<string>();
int value = ;
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 = ;
Hashtable uids = new Hashtable();
int value = ;
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 = ; i < ;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 = ; i < ; i++)
{
subjects.Rows.Add("title" + i, "uid" + i % ,"time" + );
} 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)