RosettaCodeData/Task/Knuths-algorithm-S/Elena/knuths-algorithm-s.elena

import system'dynamic;
import extensions;
import system'routines;
import system'collections;

extension algorithmOp
{
    s_of_n()
    {
        var counter := new Integer();
        var n := self;

        ^ new ArrayList().mixInto(new::
        {
            eval(i)
            {
                counter.append:1;

                if (__target.Length < n)
                {
                    __target.append:i
                }
                else
                {
                    if(randomGenerator.nextInt:counter < n)
                        { __target[randomGenerator.nextInt:n] := i }
                };

                ^ __target.Value
            }
        })
    }
}

public program()
{
    var bin := Array.allocate(10).populate:(n => new Integer());
    for(int trial := 0, trial < 10000, trial += 1)
    {
        var s_of_n := 3.s_of_n();

        for(int n := 0, n < 10, n += 1)
        {
            var sample := s_of_n.eval:n;

            if (n == 9)
                { sample.forEach:(i){ bin[i].append:1 } }
        }
    };

    console.printLine:bin.readChar()
}