ASP.net gets the duplicate data code in the array

ASP tutorial. NET get the duplicate data code in an array
The following provides five different ways to remove duplicate data from the data and count the number of repetitions.

dictionary<int, int> dic = new Dictionary ();
int[] arr = new int[] {1, 5, 2, 6, 7, 1, 5, 4, 1, 6, 8, 7, 6};
foreach (int i in arr)
{
Try
{
Dic.add (i, I);
}
catch (Exception err)
{
//.... ...
}
}

Method Two

int[] arr = new int[] {1, 5, 2, 6, 7, 1, 5, 4, 1, 6, 8, 7, 6};
int n = arr.length-arr.distinct (). Count ();

Method Three

int[] ary = new int[] {1, 3, 3, 4, 5, 4};
var q = from X in ary
Group x by x into Y
Select {Y.key,y.count ()};

Method Four

int[] arr = new int[] {1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7};
var GS = arr.groupby (i => i). by (I => i.count ());
Console.WriteLine (Gs.lastordefault (). ToArray () [0]);

Method Five

Int[] arr = {1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 5};
var linqer =
From A in arr
Group Arr by A into B
by B.count ()
Select New
{
B.key,
Count = B.count ()
};
foreach (var i in Linqer)
{
Console.WriteLine ("{0} appears {1} times", I.key, I.count);
}