using System;

using System.Linq;

using System.Collections.Generic;

​

public class MainClass

{

    public static void Main(string[] args)

    {

        int[] array = {10, 5, 10, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12};

        var dict = CountOccurence<int>(array);

        foreach (var pair in dict)

            Console.WriteLine("Value {0} occurred {1} times.", pair.Key, pair.Value);

        string[] array2 = {"10","10", "toto"};

        var dict2 = CountOccurence<string>(array2);

        foreach (var pair in dict2)

            Console.WriteLine("Value {0} occurred {1} times.", pair.Key, pair.Value);

    }

​

    public static IDictionary<T, int> CountOccurence<T>(IEnumerable<T> array)

    {

        return array.GroupBy(x => x).ToDictionary(x => x.Key, x => x.Count());

    }

}