Sort arrays of primitive types in descending order

I think it would be best not to re-invent the wheel and use Arrays.sort().

Yes, I saw the “descending” part. The sorting is the hard part, and you want to benefit from the simplicity and speed of Java’s library code. Once that’s done, you simply reverse the array, which is a relatively cheap O(n) operation. Here’s some code I found to do this in as little as 4 lines:

for (int left=0, right=b.length-1; left<right; left++, right--) {
    // exchange the first and last
    int temp = b[left]; b[left]  = b[right]; b[right] = temp;
}

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