Array Contains Performance

Question

I have a program which works with arrays and at some point I have to check if a lsit of values are inside an array, the function that does this takes about 70% of the program CP

Answer 1

As others in the comments have pointed out, the most efficient way to do this is to generate an array with the values you want and shuffle it:

public static void Shuffle(T[] arr, Random r)
{
    for (int i = arr.Length - 1; i > 0; --i)
    {
        int j = r.Next(i + 1);
        T tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }
}

public static int[] Generate(int length, Random r)
{
    var arr = new int[length];
    for(int i = 0; i < length; ++i)
    {
        arr[i] = i;
    }
    Shuffle(arr, r);
    return arr;
}

then

var arr = Generate(10, new Random());
foreach (int i in arr) { Console.WriteLine(i); }