unique random numbers - Xtreme Visual Basic Talk

10-25-2007, 03:49 PM

alex101uk

Newcomer

Join Date: Oct 2007

Posts: 1

unique random numbers

heres one for you:
i have 9 labels
each label represents a playing card
they must be randomly assigned a number between one and 11
(ace, 2, 3, 4, 5, 6, 7 ,8 ,9 ,10, Jack)
but there can be no duplicate numbers
so you could have: 3 1 5 8 6 10 2 11 4 7 9
but not: 3 1 5 3 6 10 2 3 4 7 3

i can only get it to assign random numbers with duplicates...
can someone help me out with this?
im sure i could get it if i wrote 200 odd:
if ( cardNumber1 = cardNumber2)
statements.

thanks

10-25-2007, 05:00 PM

loquin

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Join Date: Nov 2001

Location: Arizona, USA

Posts: 12,386

ref the random numbers thread in the Tutor's Corner forum. (it's also linked here: Top 10 Tutorials)

Essentially, you need to generate a list of numbers in order in an array, and then 'shuffle' the data in the array. Finally, 'deal' the numbers out of the array. Since their order was shuffled randomly, they will come in random order (and, NEVER any duplicates)

Code:

' Example Code
  Dim Cards(11) As Integer
  Dim Card As Integer
  Dim FirstCard As Integer
  Dim Rnd0 As Integer
  Dim Rnd1  As Integer
  Dim Rnd2 As Integer
  Dim N As Integer
  
  ' Populate the cards array
  For N = 1 To 11
    Cards(N) = N
  Next N
  
  'Shuffle the array
  
  'Generate random number from 1 to 11
  Rnd0 = Int(Rnd * 11) + 1
  
  'Get the card number at that position and set it aside.
  FirstCard = Cards(Rnd0)
  
  ' seed the shufle
  Rnd1 = Rnd0
  For N = 1 To 11
    Rnd2 = Int(Rnd * 11) + 1
    ' move the card
    Card = Cards(Rnd2)
    Cards(Rnd1) = Cards(Rnd2)
    Rnd1 = Rnd2
  Next N
  
  ' Move the first card into the last spot
  Cards(Rnd2) = FirstCard
  
  ' and deal
  For N = 1 To 11
    Debug.Print Cards(N)
  Next N

The way to think of this algorithm is if you laid a row of cards down on the table, and used one hand to shuffle then.

You pull one card from a random position and set it aside. This leaves a 'hole' in the row of cards. Then, you pull a card from a second random position, and place it into the existing 'hole.' Of course, this leaves a NEW 'hole.' Repeat. After enough repititions, move the first card into the last 'hole' and you're done. Deal the deck.

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Last edited by loquin; 10-25-2007 at 05:30 PM.

10-26-2007, 07:06 AM

Cerian Knight

Multi-Technologist

Super Moderator
* Expert *

Join Date: May 2004

Location: Michigan

Posts: 3,751

Here is an exhaustive thread on the subject, that should be read in whole:
http://www.xtremevbtalk.com/showthread.php?t=285630

__________________
"May the code that you write never work in ways that you didn't expect; and may the code that you didn't write never require you to maintain it". - Ancient Chinese Proverb