How to count occurences of an int in an array?

Question

My array is A = {2, 3, 4, 3, 4, 2, 4, 2, 4}

I need an array B that stock at the index i the number of occurences of i in the a

Answer 1

Check out this Fiddle

Or if you don't fancy clicking the link:

var a = new int[]{2, 3, 4, 3, 4, 2, 4, 2, 4};
var b = new int[a.Length];

    var aAsList = a.ToList();

    for (var i = 0;i < b.Length; i++)
    {
        var result = aAsList.Count(x=> x == i);
        b[i] = result;

        if (result != 0)
        {
            Console.WriteLine(string.Format("b[{0}] : {1}",i,result));
        }
    }