hello, Well I have my A* algorithm working well except one thing, the Qucksort I have written for my vector list is sorting them backwards for what I need. The largest costs are being pulled up, instead of being shoved down (which you have to do since you can't delete elements at the front of a vector, only back... correct??) So how do you make a quicksort sort backwards??

I dont know how 2 posts got up.... so can a mod delete one so ppl don't get angry!

With most sorts, you will test if one item is smaller or larger than another item. When I learned quicksort, it was implemented using the partition algorithim to test if an item was less than or equal to a pre-chosen pivot value. Just swap your less than or equal to signs with greater than or equal to signs. [edit]I think that should work, why not?

Oh, and to delete a post, click on the "Edit" button on the right side of the post. Above the little Icons, there will be a checkbox that says "Delete?". Check it, and then click modify and it will be deleted.[/edit]

i think this code should work... i haven't tried it...

Quicksort(A, p, r)
{
if (p > r)
{
q = Partition(A, p, r);
Quicksort(A, p, q);
Quicksort(A, q+1, r);
}
}


Partition(A, p, r)
{
x = A

;
i = p - 1;
j = r + 1;
while (TRUE)
{
repeat
do
{
j--;
}while (A[j]<x);

do
{
i++;
}while(A>x);

if (i > j)
Swap(A, i, j);
else
return j;
}
}

if you get some trouble and don't know what to do, let it be ascending sorted, then, swap it all.. ehheheeh.... not a good idea, but it seems quiet easy...??. ehehe...

This might seem silly, but why don't you get A* to read the list backwards?

Easy fix.

From,
Nice coder

Don't use quicksort for A*.. Use heaps or buckets instead.

... because you already have a sorted structure where you just want to add some items. quicksort is nice when you wanna sort data once.

Yea I realized that after reading more about quicksort.
Stupid me. Oh well, you don't learn anything until you actually do it...