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From: Jacob Sparre Andersen <jacob@jacob-sparre.dk>
Newsgroups: comp.lang.ada
Subject: Re: Lotto simulation
Date: Mon, 16 Jun 2014 16:25:51 +0200
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2014-06-16T16:25:51+02:00
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Markus Schöpflin wrote:

> The easiest way AFAIK is to random shuffle an integer array containing
> the numbers 1 - 49 and then selecting the first six numbers from that
> array.
>
> Random shuffling can be achieved by filling a second array of the same
> size with random numbers obtained from a generator having a uniform
> distribution and then sorting this second array; moving the numbers
> from the first array in lock-step.

Another option could be to fill one array:

      type Balls is range 1 .. 49;
      type Ordered_List_Of_Balls is array (Balls) of Balls;
      Ordered_Balls : Ordered_List_Of_Balls
   begin
      for Ball in Ordered_Balls'Range loop
         Ordered_Balls (Ball) := Ball;
      end loop;

Then shuffle the balls in that array:

      for Primary in Ordered_Balls'Range loop
         Swap (List       => Ordered_Balls,
               Position_1 => Primary,
               Position_2 => Random (Generator));
      end loop;

... where I have assumed "sensible" declarations of Swap and Generator.

Greetings,

Jacob
-- 
Statistics is like a bikini - what it shows is very suggestive,
but the most important stuff is still hidden.