five digit number with different digits

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  1. #1
    Registered User khdani's Avatar
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    five digit number with different digits

    hello,
    how can i find the amount of five digit numbers with different digits
    without using arrays, nor strings.
    i know one way is to separate the number into digits and make about 10 if's ,
    is there a better way ?

  2. #2
    DESTINY BEN10's Avatar
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    Quote Originally Posted by khdani View Post
    hello,
    how can i find the amount of five digit numbers with different digits
    without using arrays, nor strings.
    i know one way is to separate the number into digits and make about 10 if's ,
    is there a better way ?
    what do u mean by amount of five digit number. give an example.
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    and the hat of copycat stevesmithx's Avatar
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    It's not much clear what you are after.
    From what I can infer, you want to parse each digit of a number separately.
    This can be done(for decimal number system) by some division and modulo logic with 10.
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    Registered User hk_mp5kpdw's Avatar
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    So, you want the number of permutations of 10 items (digits) taken 5 at a time? If you count a high order zero digit as a possibility, then:
    P(n,r) = n! / (n-r)!
    P(10,5) = ?
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    Registered User Sharke's Avatar
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    Code:
    for (i = 10000; i < 100000; i++)
        printf("%d\n", i);

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    Registered User khdani's Avatar
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    what i want is
    how many five digit numbers with all different digits exists?
    but without using strings, nor arrays...
    the most simple way is parse each number into five variables, and check for equality every pair...
    is there a better way to do it ?

  7. #7
    and the hat of sweating
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    I think he means where each digit of the number is different.
    Ex. 12345, 12346, 12347, 23456, 23457...

    Question: Does a leading 0 count as a 5-digit number?
    Ex. 01234, 06789...
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    ATH0 quzah's Avatar
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    What is your goal? To list every single number that fits the criteria, or to simply test a given number to see if that fits? That will determine how hard this task is. Start with the latter. Get a function that will return true or false for you, letting you know if a given number fits. Then if you need the former, use that function in a loop.


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  9. #9
    Registered User khdani's Avatar
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    I think he means where each digit of the number is different.
    Ex. 12345, 12346, 12347, 23456, 23457...
    exactly

    Question: Does a leading 0 count as a 5-digit number?
    Ex. 01234, 06789...
    no, five digit numbers in range from 10000 till 99999

    What is your goal? To list every single number that fits the criteria, or to simply test a given number to see if that fits? That will determine how hard this task is. Start with the latter. Get a function that will return true or false for you, letting you know if a given number fits. Then if you need the former, use that function in a loop.
    to list every single number that fits this criteria.
    functions, strings, arrays, pointers are not allowed

  10. #10
    ATH0 quzah's Avatar
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    Well get to work. I don't see you doing anything with all of our suggestions.


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  11. #11
    Registered User khdani's Avatar
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    i know one way is to separate the number into digits and make about 10 if's ,
    is there a better way ?

    yes i did

  12. #12
    and the hat of copycat stevesmithx's Avatar
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    Quote Originally Posted by khdani View Post
    yes i did
    I am pretty sure there would always be a better way to solve any problem no matter what it is.
    So unless you post your code, i am afraid the chances of getting an useful reply are bleak.

    Edit:
    One inefficient way that i can think of is to use brute force to try all the combinations using five loops and
    filter out the unwanted numbers using one or more ifs. Of course, some better solutions than
    this are possible.
    Last edited by stevesmithx; 05-03-2009 at 11:43 AM.
    Not everything that can be counted counts, and not everything that counts can be counted
    - Albert Einstein.


    No programming language is perfect. There is not even a single best language; there are only languages well suited or perhaps poorly suited for particular purposes.
    - Herbert Mayer

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