Re: sorting int[] in descending order

Eric Sosman <>
Fri, 27 Oct 2006 11:37:38 -0400
Patricia Shanahan wrote On 10/27/06 11:20,:

Vahe Musoyan wrote:

What's the best way to sort an array of integers in descending order?
I know that one can sort in ascending order and reverse the array. Is
there any other/better way?

There are other ways, but I don't think any of the ones I know are better:

1. Write your own quicksort descending order implementation.

2. Create an Integer array with the values from the int[] and
Arrays.sort it using a supplied Comparator that reverses the
a.compareTo(b) result.

3. Replace each element of the array with the result of subtracting it
from -1, sort normally, then repeat the replacement operation. The
initial subtraction maps the largest value to the smallest, smallest to
largest etc. The final subtraction restores the original values.

4. "Count backwards:" sort the array in ascending order, but
"reflect" the index whenever you access it. Most crudely,
replace array[i] with array[array.length-1-i]. Somewhat more
smoothly, replace

    for (int i = 0; i < array.length; ++i)


    for (int i = array.length; --i >= 0; )


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