On Mon, Jan 28, 2013 at 2:34 PM, Brian Schott <[email protected]> wrote:
> I realize there are approaches like Raul and Devon are proposing that
> use 2D array indexing and require two array resequencing, but I was
> hoping to do both steps at once arithmetically to resequence the
> single index list to achieve efficiency.
What do you mean by efficiency?
Time?
Space?
Code?
Forum? (But I'll stop trying to move this to chat, I guess...)
Anyways, here's an in-place implementation:
int * whatever(int n, int * r) {
for (int j= 0; j < n; j++)
for (int k= 0; k < n; k++) {
int i1= j+n*k;
int i2= j*n-(1+k);
if (i1 < i2) {
int t= r[i1];
r[i1]= r[i2];
r[i2]= t;
}
}
return r;
}
--
Raul
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