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Re: Using Java Classes to Sort a Small Array Quickly

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On 9/11/2011 5:14 PM, Wanja Gayk wrote:
> In article<j3mupc$d5m$1@dont-email.me>, -@. says...
>>
>> On 8/31/2011 7:48 PM, KevinSimonson wrote:
>>> On the way home from work my fellow carpooler told me that there are
>>> Java classes that can do sorts in O(N) time.
>>
>>
>> Pfft.  No.  Theoretical maximum speed of a sort is something like n log
>> n.  The only data you can sort in n time is data that's already sorted.
>
> Wrong.
> Here's the proof: Sorting an array of positive integers in O(n) time:
>
>   public static void main(final String[] args) {
>    final int[] data = new int[]{3,7,6,3,5,4,1,3,1,1,1,3,4,6,0,0};
>    System.out.println(Arrays.toString(data));
>    sort(data);
>    System.out.println(Arrays.toString(data));
>   }
>
>   private static void sort(final int[] data) {
>    if (data.length>  0) {
>     long max = Long.MIN_VALUE;
>     for (final int t : data) {
>      max = Math.max(t, max);
>     }
>     final long[][] buckets = new long[(int) max+1][data.length];
>     for (final long[] bucket : buckets) {
>      Arrays.fill(bucket, Long.MIN_VALUE);
>     }
>     for (final int x : data) {
>      for (int y = 0; y<  buckets[x].length; ++y) {
>       if (buckets[x][y] == Long.MIN_VALUE) {
>        buckets[x][y] = x;
>        break;
>       }
>      }
>     }
>     int x = -1;
>     for (long[] bucket : buckets) {
>      for (long value : bucket) {
>       if (value == Long.MIN_VALUE) {
>        break;
>       }
>       data[++x] = (int) value;
>      }
>     }
>    }
>   }

     Very nice!  Would you care to try this approach on a shorter
input array, like

	data = new int[] { Integer.MAX_VALUE };

This case should be quite simple, since the array is already sorted.
Let us know how you make out, will you?

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

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Using Java Classes to Sort a Small Array Quickly KevinSimonson <kvnsmnsn@hotmail.com> - 2011-08-31 19:48 -0700
  Re: Using Java Classes to Sort a Small Array Quickly markspace <-@.> - 2011-08-31 20:39 -0700
    Re: Using Java Classes to Sort a Small Array Quickly bugbear <bugbear@trim_papermule.co.uk_trim> - 2011-09-01 09:18 +0100
    Re: Using Java Classes to Sort a Small Array Quickly Roedy Green <see_website@mindprod.com.invalid> - 2011-09-01 02:38 -0700
      Re: Using Java Classes to Sort a Small Array Quickly Patricia Shanahan <pats@acm.org> - 2011-09-01 03:50 -0700
    Re: Using Java Classes to Sort a Small Array Quickly Wanja Gayk <brixomatic@yahoo.com> - 2011-09-11 23:14 +0200
      Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-11 17:53 -0400
        Re: Using Java Classes to Sort a Small Array Quickly Wanja Gayk <brixomatic@yahoo.com> - 2011-09-12 01:40 +0200
          Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-11 20:32 -0400
            Re: Using Java Classes to Sort a Small Array Quickly Wanja Gayk <brixomatic@yahoo.com> - 2011-09-17 02:54 +0200
              Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-16 21:03 -0400
                Re: Using Java Classes to Sort a Small Array Quickly Wanja Gayk <brixomatic@yahoo.com> - 2011-09-17 16:52 +0200
                Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-17 11:05 -0400
                Re: Using Java Classes to Sort a Small Array Quickly Wanja Gayk <brixomatic@yahoo.com> - 2011-09-18 15:41 +0200
                Re: Using Java Classes to Sort a Small Array Quickly Lew <lewbloch@gmail.com> - 2011-09-18 12:53 -0700
                Re: Using Java Classes to Sort a Small Array Quickly Patricia Shanahan <pats@acm.org> - 2011-09-18 13:20 -0700
          Re: Using Java Classes to Sort a Small Array Quickly Arne Vajhøj <arne@vajhoej.dk> - 2011-09-11 21:10 -0400
            Re: Using Java Classes to Sort a Small Array Quickly Lew <lewbloch@gmail.com> - 2011-09-11 20:30 -0700
              Re: Using Java Classes to Sort a Small Array Quickly Arne Vajhøj <arne@vajhoej.dk> - 2011-09-12 19:13 -0400
                Re: Using Java Classes to Sort a Small Array Quickly Lew <lewbloch@gmail.com> - 2011-09-12 17:42 -0700
                Re: Using Java Classes to Sort a Small Array Quickly Wanja Gayk <brixomatic@yahoo.com> - 2011-09-17 02:54 +0200
                Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-16 21:13 -0400
                Re: Using Java Classes to Sort a Small Array Quickly Patricia Shanahan <pats@acm.org> - 2011-09-16 23:14 -0700
                Re: Using Java Classes to Sort a Small Array Quickly Wanja Gayk <brixomatic@yahoo.com> - 2011-09-17 16:53 +0200
                Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-12 21:24 -0400
          Re: Using Java Classes to Sort a Small Array Quickly Gene Wirchenko <genew@ocis.net> - 2011-09-12 10:57 -0700
            Re: Using Java Classes to Sort a Small Array Quickly Arne Vajhøj <arne@vajhoej.dk> - 2011-09-12 19:01 -0400
              Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-12 21:29 -0400
                Re: Using Java Classes to Sort a Small Array Quickly markspace <-@.> - 2011-09-12 19:49 -0700
                Re: Using Java Classes to Sort a Small Array Quickly Lew <lewbloch@gmail.com> - 2011-09-12 21:51 -0700
                Re: Using Java Classes to Sort a Small Array Quickly Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-09-13 11:32 -0500
                Re: Using Java Classes to Sort a Small Array Quickly Arne Vajhøj <arne@vajhoej.dk> - 2011-09-13 21:51 -0400
                Re: Using Java Classes to Sort a Small Array Quickly Gene Wirchenko <genew@ocis.net> - 2011-09-14 11:00 -0700
                Re: Using Java Classes to Sort a Small Array Quickly Patricia Shanahan <pats@acm.org> - 2011-09-13 06:33 -0700
              Re: Using Java Classes to Sort a Small Array Quickly Gene Wirchenko <genew@ocis.net> - 2011-09-13 09:48 -0700
  Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-01 00:25 -0400
    Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-01 00:54 -0400
    Re: Using Java Classes to Sort a Small Array Quickly bugbear <bugbear@trim_papermule.co.uk_trim> - 2011-09-01 09:20 +0100
      Re: Using Java Classes to Sort a Small Array Quickly Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-01 08:06 -0400
    Re: Using Java Classes to Sort a Small Array Quickly Roedy Green <see_website@mindprod.com.invalid> - 2011-09-01 02:43 -0700
  Re: Using Java Classes to Sort a Small Array Quickly Robert Klemme <shortcutter@googlemail.com> - 2011-09-01 08:32 +0200
  Re: Using Java Classes to Sort a Small Array Quickly RedGrittyBrick <RedGrittyBrick@spamweary.invalid> - 2011-09-01 10:08 +0100
    Re: Using Java Classes to Sort a Small Array Quickly Patricia Shanahan <pats@acm.org> - 2011-09-01 04:02 -0700
  Re: Using Java Classes to Sort a Small Array Quickly Roedy Green <see_website@mindprod.com.invalid> - 2011-09-01 02:37 -0700
  Re: Using Java Classes to Sort a Small Array Quickly Roedy Green <see_website@mindprod.com.invalid> - 2011-09-01 04:53 -0700
  Re: Using Java Classes to Sort a Small Array Quickly Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-09-01 09:05 -0500

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