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Thread: Removing Duplicate Values From an Array

  1. #1
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    Default Removing Duplicate Values From an Array

    I am to remove all duplicates form an array.

    For example:
    4 7 11 4 9 5 11 7 3 5
    should be changed to
    4 7 11 9 4 3

    I am not supposed to use hashtables. Is there a simple way to do this. I am trying to do it with multiple for loops.

    Thanks for all your help.


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    Default Re: Removing Duplicate Values From an Array

    The simplest way would be to use Sets but I assume you are not allowed to use them either.

    You could create a 3rd array and only add a value to it if it is not present in either of the first 2 arrays. Or you would need to loop over the smaller array and for each value loop over the larger array. When you find a match, move all values down one spot. This has 2 problems to overcome:

    You will still have values left at the end of the array eg after "removing" the first 4 the array would be 7 11 4 9 5 11 7 3 5 5, then after the next 4 it would be 7 11 9 5 11 7 3 5 5 5.

    The other problem would be if you had the same value next to each other: 4 4 3 5 1 7. If you are not careful then removing the first 4 gives 4 3 5 1 7 7. Then you continue on searching at the second element and leave the other 4 at the start of the array.
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    Default Re: Removing Duplicate Values From an Array

    Another idea. Use a contains() type method.
    Copy the first number to the new array.
    Then in a loop
    get the next number from the old array
    does the new array contain this number
    if not add it
    end loop

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    Default Re: Removing Duplicate Values From an Array

    Yeah that is what I meant by my first suggestion but I didn't word it very well. Thanks for the clarification Norm.
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    Default Re: Removing Duplicate Values From an Array

    I left out the problem of array sizes.

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    Default Re: Removing Duplicate Values From an Array

    That is why working with Collections is by far the better option. But when you are a poor 1st year student you get stuck with silly assignments doing a kludge with an array.
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    Default Re: Removing Duplicate Values From an Array

    I programmed assembly all my life. Arrays are much better.

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