what sort is this?

[Kapteyn's Star]

Hi all,
Can anyone identify this sort code? why is it very slow compard to
qsort()? and it can be improved?
Thanks.

int *next_ascending(int *arr, size_t narr, int val)
{
size_t ctr;
int *next= arr;
for(ctr= 0; ctr < narr; ++ctr)
if (arr[ctr] >= val && arr[ctr] < *next) next= &arr[ctr];
return next;
}

int *next_descending(int *arr, size_t narr, int val)
{
size_t ctr;
int *next= arr;
for(ctr= 0; ctr < narr; ++ctr)
if (arr[ctr] <= val && arr[ctr] > *next) next= &arr[ctr];
return next;
}

void sort(int *arr, size_t narr, char direction)
{
size_t ctr= 0;
int preva= INT_MIN, prevd= INT_MAX, *next, tmp;
switch (direction) {
case ASCENDING:
while (ctr < narr) {
next= next_ascending(&arr[ctr], narr-ctr, preva);
tmp= arr[ctr];
arr[ctr]= preva= *next;
*next= tmp;
ctr++;
}
break;
case DESCENDING:
while (ctr < narr) {
next= next_descending(&arr[ctr], narr-ctr, prevd);
tmp= arr[ctr];
arr[ctr]= prevd= *next;
*next= tmp;
ctr++;
}
}
}

 

[jacob navia]

DO YOUR OWN HOMEWORK!

 

[Kapteyn's Star]

DO YOUR OWN HOMEWORK!

It's not homework. Im not a student at all...just interested in
programming.

I came up with the algorithm but im certain it's already known. but im
just not able to find it on the web...only psudocode is given on
wikipaedia and i don't know which one is this method.

 

[arj]

Can anyone identify this sort code?
Looks like some kind of selection sort.

 

[regis]

Looks like some kind of selection sort.

it s a selection sort where the (arr[ctr] >= val) condition
in next_ascending() seems useless because val is the minimum
selected in the previous step by sort() in descending direction.
So the condition is always true by inviariant of the algorithm.

Same thing for (arr[ctr] <= val) condition in next_desscending()
because val is maximum selected in the previous step by sort()
in ascending direction.

so the parameter val seems useless as is the updating of
variable preva in sort()...

But i may be wrong...

 

[Ron Ford]

It's not homework. Im not a student at all...just interested in
programming.

I came up with the algorithm but im certain it's already known. but im
just not able to find it on the web...only psudocode is given on
wikipaedia and i don't know which one is this method.

Jacob's a Texas ex-pat in Paris. He also shouted "you're queer if you
don't like penthouse," and "you poisoned me on the chanz a lyzee."

I can provide a selection sort from a syntax with C bindings, if that would
help.

Britain's Heide has the final word on this sort, probably coarse.