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Random Generation of unique array.

This is a discussion on Random Generation of unique array. within the C Programming forums, part of the General Programming Boards category; Hello everyone.... I am trying to generate a random unique array which would have in it all the whole numbers ...

  1. #1
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    Random Generation of unique array.

    Hello everyone....

    I am trying to generate a random unique array which would have in it all the whole numbers up to n.
    For an example.
    If n=10
    Then it may give the following output
    9
    5
    4
    2
    3
    1
    0
    8
    6
    7

    Can it be done without using the random function in loops?

  2. #2
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    sorry , but i can give it a try with reverse transpose ... me new to C language !

  3. #3
    C++ Witch laserlight's Avatar
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    There are two general approaches:
    1. Loop over the elements of the array and generate a random number, within the given range, for each of them. Before moving on to the next element, check that the number generated is not a duplicate. If it is, generate a random number again, repeating the check until the number generated is not a duplicate.
    2. Populate the array with numbers from the given range (in this case: numbers from 0 to n in say, ascending order). Shuffle array.

    It sounds like option #2 is likely to be good here.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  4. #4
    ATH0 quzah's Avatar
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    3. Pop and squish.
    Code:
    #include<stdio.h>
    #include<stdlib.h>
    #include<time.h>
    #define O0 10
    #define OO(oo) for( oo = 0x0; oo < O0; oo++ )
    int Ox0( int OX0[], int oO )
    {
        int ox0 = OX0[ 0x0 ];
        if( oO > 0x0 )
        {
            int o0 = 0x0, x0 = rand() % oO;
            ox0 = OX0[ x0 ];
    
            for( o0 = x0 + 1; o0 < oO; o0++ )
                OX0[ o0 - 1 ] = OX0[ o0 ];
        }
        return ox0;
    }
    
    int main( void )
    {
        int oO[ O0 ] = { 0x0 }, Oo[ O0 ] = { 0x0 }, oo = 0x0;
        
        srand( time( NULL ) );
        
        OO( oo ) Oo[ oo ] = oo;
        OO( oo ) oO[ oo ] = Ox0( Oo, O0 - oo );
        OO( oo ) printf( "%d\n", oO[ oo ] );
    
        return 0x0;
    }

    Quzah.
    iMalc likes this.
    Hope is the first step on the road to disappointment.

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