Good ramdomize/distribution algorithm?

This is a discussion on Good ramdomize/distribution algorithm? within the C Programming forums, part of the General Programming Boards category; Hi, I got a problem. Lets say I got a list with 100 free spots. I want save something in ...

  1. #1
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    Good ramdomize/distribution algorithm?

    Hi, I got a problem.

    Lets say I got a list with 100 free spots.

    I want save something in 60 spots, and I want do distribute them as evenly as possible. That is I don't want spot 1-59.

    Anyone got any suggestions on how to solve this in a good way?

    Thanks

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    I'm sorry, I don't really understand what you mean by "That is I don't want stop 1-59".
    Can you please explain?

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    Code:
    r = rand() % 100;
    perhaps?

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    Quote Originally Posted by Abda92 View Post
    I'm sorry, I don't really understand what you mean by "That is I don't want stop 1-59".
    Can you please explain?
    ok, lets say the list is 10 long

    That is I don't want place: 1,2,3,4, I want like: 1,3,5,7, I don't wan't clusters.

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    Are you talking about spreading the load over multiple CPU's here?

    If so, you probably need to KNOW what you are trying to achieve, and implement an algorithm for that. My suggestion will still work to spread it around, but there's absolutely no guarantee that you don't get 1, 2, 4, 7 as a sequence of 4.

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    C++ Witch laserlight's Avatar
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    Basically, you want to choose 60 integers from 1 to 100 inclusive such that they are distributed as evenly as possible. One way is to choose all the odd numbers, then choose every 10th even number.

    EDIT:
    But if matsp's guess is correct, then obviously this choice is not a one time thing. Consequently, just choose at random, in the long run things will even out even if the first time you get 1-59.
    Last edited by laserlight; 11-07-2007 at 09:23 AM.
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    Algorithm Dissector iMalc's Avatar
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    Quote Originally Posted by micke_b View Post
    Lets say I got a list with 100 free spots.
    The problem makes no sense. Lists don't have 'free spots'. Lists only contain exactly what items you put in them and are always accessed sequentially.
    Perhaps you mean an 'array'?

    Are you doing hashing, and want to distribute items into an array without clumping so as to reduce collisions or something?
    You really could be doing anything from your description, so we need WAAAY more info!
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