Re: sorting int[] in descending order

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.

Option 1 involves a lot of coding. Options 2 and 3 each involve more
overhead than reversing the array after an ascending order sort.

If, for its other uses, this array is on the borderline between being
best represented by an int[] or an Integer[], then the descending sort
requirement might tip it over to Integer[], and you could do the sort
with descending order Comparator without any copying.

Patricia
.

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